Feature: Walk-Einladungen und RSVP-System

Gassi-Treffen bekommen ein vollständiges Einladungs- und RSVP-System:
- Neue Tabelle walk_invitations (walk_id, user_id, status, Zeitstempel)
- Backend: /invite-candidates, /invite, /rsvp, /participants Endpoints
- Push-Notification beim Einladen
- Frontend: RSVP-Buttons (Zusagen/Vielleicht/Absagen), Teilnehmerliste
  mit Avatar-Initialen und farbkodierten RSVP-Badges, Einladen-Modal
- SW by-v205, APP_VER 173

backend/static/js/pages/walks.js

@@ -269,13 +269,46 @@ window.Page_walks = (() => {
     });
   }
 
+  // ----------------------------------------------------------
+  // RSVP-Status → Label + Farbe
+  // ----------------------------------------------------------
+  function _rsvpBadge(status) {
+    if (status === 'yes')     return `<span class="walks-rsvp-badge walks-rsvp--yes">Zusage</span>`;
+    if (status === 'maybe')   return `<span class="walks-rsvp-badge walks-rsvp--maybe">Vielleicht</span>`;
+    if (status === 'no')      return `<span class="walks-rsvp-badge walks-rsvp--no">Absage</span>`;
+    return `<span class="walks-rsvp-badge walks-rsvp--invited">Eingeladen</span>`;
+  }
+
+  function _avatarInitials(name) {
+    const parts = (name || '?').trim().split(/\s+/);
+    const initials = parts.length >= 2
+      ? parts[0][0] + parts[parts.length - 1][0]
+      : parts[0].slice(0, 2);
+    return initials.toUpperCase();
+  }
+
+  function _invitationRowHTML(inv) {
+    return `
+      <div class="walks-invitation-row">
+        <div class="walks-inv-avatar">${_avatarInitials(inv.user_name)}</div>
+        <div class="walks-inv-info">
+          <div class="walks-inv-name">${_esc(inv.user_name)}</div>
+          ${inv.hunde ? `<div class="walks-inv-hunde">${UI.icon('dog')} ${_esc(inv.hunde)}</div>` : ''}
+        </div>
+        <div class="walks-inv-badge">${_rsvpBadge(inv.status)}</div>
+      </div>`;
+  }
+
   // ----------------------------------------------------------
   // Detail-Modal
   // ----------------------------------------------------------
   async function _openDetail(walkId) {
-    let walk;
+    let walk, participantData;
     try {
       walk = await API.walks.get(walkId);
+      if (_appState.user) {
+        try { participantData = await API.walks.participants(walkId); } catch {}
+      }
     } catch (err) {
       UI.toast.error(err.message);
       return;
@@ -286,15 +319,42 @@ window.Page_walks = (() => {
     const isFull     = walk.status === 'voll' || walk.teilnehmer_count >= walk.max_teilnehmer;
     const isPast     = _isPast(walk.datum);
     const spots      = walk.max_teilnehmer - walk.teilnehmer_count;
+    const myRsvp     = participantData?.my_rsvp ?? null;
+    const isInvited  = !!myRsvp;
+    const invitations = participantData?.invitations ?? [];
 
-    // Teilnehmerliste
+    // Teilnehmerliste (join-Teilnehmer, klassisch)
     const teilnehmerHTML = walk.teilnehmer?.length
       ? walk.teilnehmer.map(t => `
           <div class="walks-participant">
-            <span class="walks-participant-name">${UI.icon('user')} ${_esc(t.user_name)}</span>
+            <div class="walks-inv-avatar walks-inv-avatar--sm">${_avatarInitials(t.user_name)}</div>
+            <span class="walks-participant-name">${_esc(t.user_name)}</span>
             ${t.hunde ? `<span class="walks-participant-hunde">${UI.icon('dog')} ${_esc(t.hunde)}</span>` : ''}
           </div>`).join('')
-      : `<p style="color:var(--c-text-muted)">Noch keine Teilnehmer.</p>`;
+      : '';
+
+    // Einladungsliste
+    const invListHTML = invitations.length
+      ? invitations.map(inv => _invitationRowHTML(inv)).join('')
+      : `<p style="color:var(--c-text-muted);font-size:var(--text-sm)">Noch keine Einladungen.</p>`;
+
+    // RSVP-Section für eingeladene Nutzer
+    const rsvpSectionHTML = (isInvited && !isOwn) ? `
+      <div class="walks-rsvp-section" id="wd-rsvp-section">
+        <div class="walks-detail-section-label">${UI.icon('check-circle')} Deine Antwort</div>
+        <div class="walks-rsvp-buttons">
+          <button type="button" class="walks-rsvp-btn ${myRsvp === 'yes' ? 'active' : ''}" data-rsvp="yes">
+            ${UI.icon('check')} Zusagen
+          </button>
+          <button type="button" class="walks-rsvp-btn ${myRsvp === 'maybe' ? 'active' : ''}" data-rsvp="maybe">
+            ${UI.icon('question')} Vielleicht
+          </button>
+          <button type="button" class="walks-rsvp-btn ${myRsvp === 'no' ? 'active' : ''}" data-rsvp="no">
+            ${UI.icon('x')} Absagen
+          </button>
+        </div>
+      </div>
+    ` : '';
 
     const body = `
       <div class="walks-detail-header">
@@ -316,11 +376,23 @@ window.Page_walks = (() => {
         <p style="margin:var(--space-4) 0;color:var(--c-text-secondary)">${_esc(walk.beschreibung)}</p>
       ` : ''}
 
+      ${rsvpSectionHTML}
+
       <div class="walks-detail-section">
-        <div class="walks-detail-section-label">${UI.icon('users')} Teilnehmer (${walk.teilnehmer_count}/${walk.max_teilnehmer})</div>
-        ${teilnehmerHTML}
+        <div style="display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--space-2)">
+          <div class="walks-detail-section-label" style="margin-bottom:0">${UI.icon('users')} Einladungen</div>
+          ${isOwn && !isPast ? `<button type="button" class="btn btn-secondary btn-sm" id="wd-invite-btn">${UI.icon('user-plus')} Einladen</button>` : ''}
+        </div>
+        <div id="wd-inv-list">${invListHTML}</div>
       </div>
 
+      ${walk.teilnehmer?.length ? `
+        <div class="walks-detail-section">
+          <div class="walks-detail-section-label">${UI.icon('check-circle')} Beigetreten (${walk.teilnehmer_count}/${walk.max_teilnehmer})</div>
+          ${teilnehmerHTML}
+        </div>
+      ` : ''}
+
       <p style="color:var(--c-text-muted);font-size:0.8rem;margin-top:var(--space-4)">
         Veranstaltet von ${_esc(walk.veranstalter_name || 'Unbekannt')}
       </p>
@@ -380,6 +452,31 @@ window.Page_walks = (() => {
       _showEditForm(walk);
     });
 
+    // Einladen-Button
+    document.getElementById('wd-invite-btn')?.addEventListener('click', () => {
+      UI.modal.close();
+      _showInviteModal(walk);
+    });
+
+    // RSVP-Buttons
+    document.querySelectorAll('.walks-rsvp-btn').forEach(btn => {
+      btn.addEventListener('click', async () => {
+        const status = btn.dataset.rsvp;
+        try {
+          await API.walks.rsvp(walk.id, status);
+          // Buttons aktualisieren
+          document.querySelectorAll('.walks-rsvp-btn').forEach(b => {
+            b.classList.toggle('active', b.dataset.rsvp === status);
+          });
+          UI.toast.success(
+            status === 'yes' ? 'Zugesagt!' :
+            status === 'maybe' ? 'Antwort: Vielleicht.' :
+            'Abgesagt.'
+          );
+        } catch (err) { UI.toast.error(err.message); }
+      });
+    });
+
     // Stornieren: Zwei-Klick-Pattern (kein UI.modal.confirm im Modal)
     let _cancelPending = false;
     document.getElementById('wd-cancel-walk')?.addEventListener('click', async () => {
@@ -442,6 +539,66 @@ window.Page_walks = (() => {
     });
   }
 
+  // ----------------------------------------------------------
+  // Freunde einladen
+  // ----------------------------------------------------------
+  async function _showInviteModal(walk) {
+    let candidates;
+    try {
+      candidates = await API.walks.inviteCandidates(walk.id);
+    } catch (err) {
+      UI.toast.error(err.message);
+      return;
+    }
+
+    const listHTML = candidates.length
+      ? candidates.map(f => `
+          <div class="walks-invite-row" data-friend-id="${f.friend_id}" data-friend-name="${_esc(f.friend_name)}">
+            <div class="walks-inv-avatar">${_avatarInitials(f.friend_name)}</div>
+            <div class="walks-inv-name" style="flex:1">${_esc(f.friend_name)}</div>
+            <button type="button" class="btn btn-primary btn-sm walks-invite-send">
+              ${UI.icon('paper-plane-tilt')} Einladen
+            </button>
+          </div>`).join('')
+      : `<p style="color:var(--c-text-muted)">Alle Freunde wurden bereits eingeladen.</p>`;
+
+    const body = `
+      <p style="color:var(--c-text-secondary);margin-bottom:var(--space-3)">
+        ${_fmtDate(walk.datum)} · ${walk.uhrzeit} Uhr
+        ${walk.ort_name ? `· ${_esc(walk.ort_name)}` : ''}
+      </p>
+      <div id="invite-list">${listHTML}</div>
+    `;
+
+    const footer = `
+      <button type="button" class="btn btn-secondary flex-1" id="invite-back">Zurück</button>
+    `;
+
+    UI.modal.open({ title: `${UI.icon('user-plus')} Freunde einladen`, body, footer });
+
+    document.getElementById('invite-back')?.addEventListener('click', () => {
+      UI.modal.close();
+      _openDetail(walk.id);
+    });
+
+    document.querySelectorAll('.walks-invite-send').forEach(btn => {
+      btn.addEventListener('click', async () => {
+        const row      = btn.closest('.walks-invite-row');
+        const friendId = parseInt(row.dataset.friendId);
+        const name     = row.dataset.friendName;
+        await UI.asyncButton(btn, async () => {
+          await API.walks.invite(walk.id, friendId);
+          row.innerHTML = `
+            <div class="walks-inv-avatar">${_avatarInitials(name)}</div>
+            <div class="walks-inv-name" style="flex:1">${_esc(name)}</div>
+            <span class="walks-rsvp-badge walks-rsvp--invited">Eingeladen</span>
+          `;
+          UI.toast.success(`${name} eingeladen.`);
+        });
+      });
+    });
+  }
+
   // ----------------------------------------------------------
   // Beitreten-Formular (Hunde wählen)
   // ----------------------------------------------------------
@@ -547,7 +704,15 @@ window.Page_walks = (() => {
 
           <!-- Mini-Karte -->
           <div style="position:relative">
-            <div id="wf-map-wrap" style="border-radius:var(--radius-md);overflow:hidden;height:180px;background:var(--c-surface-2)"></div>
+            <div id="wf-map-wrap" style="border-radius:var(--radius-md);overflow:hidden;height:200px;background:var(--c-surface-2)"></div>
+            <button type="button" id="wf-map-pin-here" style="
+              position:absolute;bottom:10px;left:50%;transform:translateX(-50%);
+              z-index:1000;background:var(--c-primary);color:#fff;border:none;
+              border-radius:var(--radius-full);padding:6px 14px;font-size:var(--text-xs);
+              font-weight:600;box-shadow:var(--shadow-md);cursor:pointer;
+              display:flex;align-items:center;gap:6px;white-space:nowrap">
+              ${UI.icon('map-pin')} Pin hier setzen
+            </button>
           </div>
 
           <!-- Ort-Chip -->
@@ -615,7 +780,7 @@ window.Page_walks = (() => {
 
     function _placeMarker(lat, lon) {
       if (_miniMarker) { _miniMarker.setLatLng([lat, lon]); return; }
-      _miniMarker = L.marker([lat, lon], { draggable: false, icon: _mkIcon() }).addTo(_miniMap);
+      _miniMarker = L.marker([lat, lon], { draggable: true, icon: _mkIcon() }).addTo(_miniMap);
       _miniMarker.on('dragend', () => {
         const p = _miniMarker.getLatLng();
         _locLat = p.lat; _locLon = p.lng;
@@ -649,16 +814,18 @@ window.Page_walks = (() => {
         L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', { maxZoom: 19 })
           .addTo(_miniMap);
         _miniMap.invalidateSize();
-        if (_locLat) {
-          _placeMarker(lat, lon);
-          _miniMarker.dragging.disable();
-        }
+        if (_locLat) _placeMarker(lat, lon);
         _miniMap.on('click', e => {
-          if (!_mapEditing) return;
           _setCoords(e.latlng.lat, e.latlng.lng);
           _placeMarker(_locLat, _locLon);
           document.getElementById('wf-location-btn-label').textContent = 'POI suchen';
         });
+        document.getElementById('wf-map-pin-here')?.addEventListener('click', () => {
+          const c = _miniMap.getCenter();
+          _setCoords(c.lat, c.lng);
+          _placeMarker(c.lat, c.lng);
+          document.getElementById('wf-location-btn-label').textContent = 'POI suchen';
+        });
       }, 150);
     });