Feature: Tagebuch Cover-Bild (Favorit-Funktion) für diary_media

- Migration: diary_media.is_cover (INTEGER DEFAULT 0)
- Upload: erstes Item eines Eintrags automatisch is_cover=1
- Neuer Endpoint: PATCH /diary/{id}/media/{mid}/cover
- GET-Endpoints geben is_cover + cover_url zurück
- Frontend: Stern-Button (⭐) in Gallery-Detail und Edit-Formular
- Timeline-Karte verwendet cover_url als Vorschaubild
- SW by-v212, APP_VER 186

backend/routes/diary.py

@@ -87,12 +87,12 @@ def _set_dog_ids(conn, entry_id: int, dog_ids: list[int]):
 
 
 def _fetch_media_items(conn, entry_ids: list[int]) -> dict:
-    """Gibt {entry_id: [{url, media_type, sort_order, id}, ...]} zurück."""
+    """Gibt {entry_id: [{url, media_type, sort_order, id, is_cover}, ...]} zurück."""
     if not entry_ids:
         return {}
     ph = ",".join("?" * len(entry_ids))
     rows = conn.execute(
-        f"SELECT id, diary_id, url, media_type, sort_order FROM diary_media "
+        f"SELECT id, diary_id, url, media_type, sort_order, is_cover FROM diary_media "
         f"WHERE diary_id IN ({ph}) ORDER BY diary_id, sort_order",
         entry_ids
     ).fetchall()
@@ -100,7 +100,8 @@ def _fetch_media_items(conn, entry_ids: list[int]) -> dict:
     for r in rows:
         result.setdefault(r["diary_id"], []).append({
             "id": r["id"], "url": r["url"],
-            "media_type": r["media_type"], "sort_order": r["sort_order"]
+            "media_type": r["media_type"], "sort_order": r["sort_order"],
+            "is_cover": r["is_cover"],
         })
     return result
 
@@ -109,7 +110,11 @@ def _entry_dict(row, dog_ids_map: dict, media_map: dict = None) -> dict:
     e = dict(row)
     e["tags"]        = json.loads(e["tags"]) if e["tags"] else []
     e["dog_ids"]     = dog_ids_map.get(e["id"], [e["dog_id"]])
-    e["media_items"] = (media_map or {}).get(e["id"], [])
+    items            = (media_map or {}).get(e["id"], [])
+    e["media_items"] = items
+    # cover_url: Item mit is_cover=1, Fallback auf erstes Item
+    cover = next((m for m in items if m.get("is_cover")), items[0] if items else None)
+    e["cover_url"]   = cover["url"] if cover else None
     return e
 
 
@@ -437,16 +442,19 @@ async def upload_media(dog_id: int, entry_id: int,
             "SELECT COALESCE(MAX(sort_order), -1) FROM diary_media WHERE diary_id=?",
             (entry_id,)
         ).fetchone()[0]
+        # Erstes Item eines Eintrags wird automatisch Cover
+        is_cover = 1 if max_order == -1 else 0
         conn.execute(
-            "INSERT INTO diary_media (diary_id, url, media_type, sort_order) VALUES (?,?,?,?)",
-            (entry_id, media_url, media_type, max_order + 1)
+            "INSERT INTO diary_media (diary_id, url, media_type, sort_order, is_cover) VALUES (?,?,?,?,?)",
+            (entry_id, media_url, media_type, max_order + 1, is_cover)
         )
         new_id = conn.execute(
             "SELECT id FROM diary_media WHERE diary_id=? ORDER BY id DESC LIMIT 1",
             (entry_id,)
         ).fetchone()["id"]
 
-    return {"id": new_id, "url": media_url, "media_type": media_type, "sort_order": max_order + 1}
+    return {"id": new_id, "url": media_url, "media_type": media_type,
+            "sort_order": max_order + 1, "is_cover": is_cover}
 
 
 @router.delete("/{dog_id}/diary/{entry_id}/media/{media_id}", status_code=204)
@@ -484,3 +492,24 @@ async def delete_media_legacy(dog_id: int, entry_id: int, user=Depends(get_curre
             try: os.remove(path)
             except OSError: pass
         conn.execute("UPDATE diary SET media_url=NULL WHERE id=?", (entry_id,))
+
+
+@router.patch("/{dog_id}/diary/{entry_id}/media/{media_id}/cover", status_code=200)
+async def set_cover_media(dog_id: int, entry_id: int, media_id: int,
+                          user=Depends(get_current_user)):
+    """Setzt ein Medium als Cover-Bild (is_cover=1), alle anderen auf 0."""
+    with db() as conn:
+        _own_dog(dog_id, user["id"], conn)
+        row = conn.execute(
+            "SELECT dm.id FROM diary_media dm "
+            "JOIN diary d ON d.id = dm.diary_id "
+            "LEFT JOIN diary_dogs dd ON dd.diary_id = d.id "
+            "WHERE dm.id=? AND dm.diary_id=? AND (d.dog_id=? OR dd.dog_id=?)",
+            (media_id, entry_id, dog_id, dog_id)
+        ).fetchone()
+        if not row:
+            raise HTTPException(404, "Medium nicht gefunden.")
+        # Alle Items dieses Eintrags auf is_cover=0, dann das gewählte auf 1
+        conn.execute("UPDATE diary_media SET is_cover=0 WHERE diary_id=?", (entry_id,))
+        conn.execute("UPDATE diary_media SET is_cover=1 WHERE id=?", (media_id,))
+    return {"ok": True}