Design-System Sprint A: utilities.css + 948 Inline-Styles → Utility-Klassen, SW by-v1102

PHASE 1 — Sofort-Cleanup ohne Risiko:
- Neue Datei utilities.css mit ~25 Klassen für häufige Kombinationen:
  * text-xs-muted, text-xs-secondary, text-sm-muted, text-sm-secondary
  * flex-gap-2/3, flex-col-gap-2/3/4, flex-center-gap-1/2/3
  * flex-between, flex-1-min, mb-1/3, mt-1/3
  * icon-xs/sm/md/lg, label-block, caption
- index.html bindet utilities.css ein
- mb-3/mt-3 ergänzt (waren in design-system.css unvollständig)

PHASE 2 — .by-tab Modifier für Vereinheitlichung:
- .by-tabs.grid (mit --tab-cols Variable für Admin/Health/etc.)
- .by-tabs.sticky (Desktop vertikale Tabs für Admin)
- .by-tabs.wrap (Zuchthunde, flex-wrap statt scroll)
- .by-tabs.separated (Sitting, mit eigenem Hintergrund + Border)

PHASE 3 — Inline-Style → Klassen-Migration (Python-Script):
- 948 Inline-Styles entfernt (5101 → 4153, -18%)
- 962 Migrationen über 47 Page-Dateien
- Top-Treffer: admin.js (180), health.js (67), dog-profile.js (67),
  litters.js (62), settings.js (61), zuchthunde.js (51)
- Patterns: text-muted, text-secondary, text-danger, text-xs-muted,
  text-sm-muted, grid-2 (Duplikat-Bug behoben!), flex-col-gap-3,
  p-3/4, mb-2/3/4, hidden, w-full, flex-1, ...
- Bewahrt bestehende class-Attribute (mergt korrekt)

Alle 19 Tests grün. Kein visueller Diff erwartet (gleiche Property-Werte).

backend/static/js/pages/map.js

@@ -221,7 +221,7 @@ window.Page_map = (() => {
 
         <div class="map-statusbar" id="map-statusbar">
           <span id="map-zoom-info"></span>
-          <span id="map-osm-status" style="display:none"></span>
+          <span id="map-osm-status" class="hidden"></span>
           <span class="map-statusbar-sep map-weather-chip--hidden" id="map-weather-sep">·</span>
           <span class="map-weather-chip--hidden" id="map-weather-info"></span>
         </div>
@@ -1780,7 +1780,7 @@ window.Page_map = (() => {
                                   border:1.5px solid var(--c-border);border-radius:100px;cursor:pointer;
                                   font-size:var(--text-xs);font-weight:600;user-select:none">
               <input type="checkbox" name="dog_ids" value="${d.id}" ${checked ? 'checked' : ''}
-                     style="display:none" class="rec-dog-cb">
+                     class="rec-dog-cb hidden">
               ${av}<span>${UI.escape(d.name)}</span>
             </label>`;
           }).join('')}
@@ -1798,7 +1798,7 @@ window.Page_map = (() => {
           <input class="form-control" type="text" name="name"
                  placeholder="Wird automatisch ermittelt…" required>
         </div>
-        <div style="display:grid;grid-template-columns:1fr 1fr;gap:var(--space-3)">
+        <div class="grid-2">
           <div class="form-group">
             <label class="form-label">Schwierigkeit</label>
             <select class="form-control" name="schwierigkeit">
@@ -1842,7 +1842,7 @@ window.Page_map = (() => {
           </label>
         </div>
         <div class="form-group">
-          <label class="form-label">Beschreibung <span style="color:var(--c-text-secondary)">(optional)</span></label>
+          <label class="form-label">Beschreibung <span class="text-secondary">(optional)</span></label>
           <textarea class="form-control" name="beschreibung" rows="2"
                     placeholder="Besonderheiten, Highlights, Tipps…"></textarea>
         </div>