Feature: Aktivitäten in Freunde-Ansicht anklickbar

- diary → Tagebuch, health → Gesundheit, walk → Gassi-Treffen
- Items als <button> für iOS-Tap-Zuverlässigkeit
- fr-activity-item--link mit Hover/Tap-Stil

backend/static/js/pages/friends.js

@@ -246,11 +246,26 @@ window.Page_friends = (() => {
         _renderActivity(_activityAll);
       });
     });
+
+    el.querySelectorAll('.fr-activity-item[data-nav]').forEach(btn => {
+      btn.addEventListener('click', () => {
+        const page = btn.dataset.nav;
+        if (page) App.navigate(page);
+      });
+    });
   }
 
+  const _ACTIVITY_PAGE = {
+    diary:   'diary',
+    health:  'health',
+    walk:    'walks',
+    new_dog: null,
+  };
+
   function _activityItem(item) {
-    const ago  = _timeAgo(item.created_at);
-    const text = item.text || '';
+    const ago     = _timeAgo(item.created_at);
+    const text    = item.text || '';
+    const page    = _ACTIVITY_PAGE[item.type] || '';
     const dogLabel = item.dog_name
       ? `<span class="fr-activity-dog">${_esc(item.dog_name)}</span>`
       : '';
@@ -265,8 +280,10 @@ window.Page_friends = (() => {
              ${_esc((item.user_name || '?')[0].toUpperCase())}
            </div>`;
 
+    const tag = page ? `button type="button"` : `div`;
     return `
-      <div class="fr-activity-item">
+      <${tag} class="fr-activity-item${page ? ' fr-activity-item--link' : ''}"
+              ${page ? `data-nav="${page}"` : ''}>
         <div class="fr-activity-avatar-wrap">
           ${avatar}
           <div class="fr-activity-icon-badge">
@@ -283,7 +300,7 @@ window.Page_friends = (() => {
           ${text ? `<div class="fr-activity-text">${_esc(text)}</div>` : ''}
           <div class="fr-activity-time">${_esc(ago)}</div>
         </div>
-      </div>
+      </${page ? 'button' : 'div'}>
     `;
   }