Perf: 9 Performance-Fixes — SW by-v1072

Backend:
- DB: 3 neue Indizes (forum_posts thread+user, routes user) — Forum/Routen-Queries
- Caching: cache.py (TTL-Cache ohne neue Dependency) für 5 statische Listen
  (training_exercises, pflege_tipps, wiki_stats, wiki_gruppen, help_articles)
- diary.py + breeder_photos.py: Bildverarbeitung (ffmpeg/PIL/EXIF) per
  run_in_executor → blockiert Event-Loop nicht mehr
- scheduler.py: 11 kollidierende Jobs auf 5-Min-Intervalle gestaggert, coalesce=True
- social.py: ORDER BY RANDOM() ohne LIMIT in 2 Stellen gefixt
- alerts.py: Haversine-Loop bekommt SQL-Bounding-Box-Vorfilter

Frontend:
- sw.js: Tile-Cache mit LRU-Eviction (max 500 Einträge)
- admin.js: Event-Listener-Leak — Tab-Klicks per Delegation statt N Listener
- api.js: compressImage() Helper — Client-seitiges Resize auf max 2000px
  (HEIC/Videos/<500KB unverändert), integriert in 8 Upload-Stellen
  (diary, dog-profile×2, walks, poison, lost, health×2)

Bump APP_VER 1071 → 1072 (sw.js, app.js, main.py, index.html)

backend/routes/help.py

@@ -5,10 +5,28 @@ from pydantic import BaseModel
 from typing import Optional
 from database import db
 from auth import get_current_user_optional, require_admin
+from cache import ttl_cache
 
 router = APIRouter()
 
 
+# ------------------------------------------------------------------
+# Öffentliche, aktive FAQ-Liste – statisch, 1h TTL-Cache.
+# Admin-Pfad (?all=1) wird NICHT gecached.
+# Wird bei jedem schreibenden Admin-Endpoint unten invalidiert.
+# ------------------------------------------------------------------
+@ttl_cache(ttl=3600)
+def _load_active_help_articles() -> list[dict]:
+    with db() as conn:
+        rows = conn.execute(
+            "SELECT id, kategorie, frage, antwort, sort_order, aktiv "
+            "FROM help_articles "
+            "WHERE aktiv = 1 "
+            "ORDER BY kategorie, sort_order, id"
+        ).fetchall()
+    return [dict(r) for r in rows]
+
+
 # ------------------------------------------------------------------
 # Schemas
 # ------------------------------------------------------------------
@@ -39,22 +57,17 @@ def get_help(
     is_admin = user and user.get("rolle") == "admin"
     show_all = all == 1 and is_admin
 
-    with db() as conn:
-        if show_all:
+    if show_all:
+        with db() as conn:
             rows = conn.execute(
                 "SELECT id, kategorie, frage, antwort, sort_order, aktiv "
                 "FROM help_articles "
                 "ORDER BY kategorie, sort_order, id"
             ).fetchall()
-        else:
-            rows = conn.execute(
-                "SELECT id, kategorie, frage, antwort, sort_order, aktiv "
-                "FROM help_articles "
-                "WHERE aktiv = 1 "
-                "ORDER BY kategorie, sort_order, id"
-            ).fetchall()
+        return [dict(r) for r in rows]
 
-    return [dict(r) for r in rows]
+    # Öffentliche, aktive Artikel kommen aus dem Cache
+    return _load_active_help_articles()
 
 
 # ------------------------------------------------------------------
@@ -68,6 +81,7 @@ def create_article(body: ArticleCreate, admin=Depends(require_admin)):
             "VALUES (?, ?, ?, ?, ?)",
             (body.kategorie, body.frage, body.antwort, body.sort_order, body.aktiv),
         )
+    _load_active_help_articles.cache_clear()
     return {"ok": True, "id": cur.lastrowid}
 
 
@@ -85,6 +99,7 @@ def update_article(article_id: int, body: ArticleUpdate, admin=Depends(require_a
             f"UPDATE help_articles SET {set_clause} WHERE id=?",
             (*updates.values(), article_id),
         )
+    _load_active_help_articles.cache_clear()
     return {"ok": True}
 
 
@@ -95,4 +110,5 @@ def update_article(article_id: int, body: ArticleUpdate, admin=Depends(require_a
 def delete_article(article_id: int, admin=Depends(require_admin)):
     with db() as conn:
         conn.execute("DELETE FROM help_articles WHERE id=?", (article_id,))
+    _load_active_help_articles.cache_clear()
     return {"ok": True}