Feature: 3 Community-Features — Foto-Challenge, Stamm-Gassis, Rassen-Chip (SW by-v700)

- Foto-Challenge der Woche: DB-Tabellen, routes/challenges.py (current/submit/vote/winners),
  Scheduler-Job jeden Montag 08:00, walks.js Challenge-Tab mit Banner, Galerie, Voting-Herz
- Gassi-Zeiten-Pool: DB-Tabelle gassi_zeiten, routes/gassi_zeiten.py (CRUD + Umkreis),
  walks.js Stamm-Gassis-Tab mit Karten, Wochentag-Selector, Mitmachen→Chat
- Rassen-Treffen-Chip: GET /api/friends/same-breed, dog-profile.js zeigt Chip
  wenn andere User gleiche Rasse haben, Klick → Forum mit Rassen-Suche vorausgefüllt

backend/routes/friends.py

@@ -342,3 +342,56 @@ async def remove_friend(friend_user_id: int, user=Depends(get_current_user)):
               AND ((requester_id=? AND addressee_id=?) OR (requester_id=? AND addressee_id=?))
         """, (uid, friend_user_id, friend_user_id, uid))
     return {"ok": True}
+
+
+# ------------------------------------------------------------------
+# GET /api/friends/same-breed — andere User mit gleicher Rasse
+# ------------------------------------------------------------------
+@router.get("/same-breed")
+async def same_breed(user=Depends(get_current_user)):
+    """Findet andere User mit Hunden derselben Rasse. Gibt Anzahl + Forum-Suche zurück."""
+    uid = user["id"]
+    with db() as conn:
+        # Rassen des eingeloggten Users
+        my_dogs = conn.execute(
+            "SELECT rasse FROM dogs WHERE user_id=? AND rasse IS NOT NULL AND rasse != ''",
+            (uid,)
+        ).fetchall()
+
+        if not my_dogs:
+            return {"count": 0, "rassen": [], "forum_query": None}
+
+        rassen = list({d["rasse"].strip() for d in my_dogs if d["rasse"]})
+
+        # Andere User (nicht ich) die eine dieser Rassen haben
+        ph = ",".join("?" * len(rassen))
+        count_row = conn.execute(f"""
+            SELECT COUNT(DISTINCT d.user_id) AS cnt
+            FROM dogs d
+            WHERE d.user_id != ?
+              AND d.rasse IN ({ph})
+        """, (uid, *rassen)).fetchone()
+
+        count = count_row["cnt"] if count_row else 0
+
+        # Für jede Rasse: wie viele andere User
+        rassen_detail = []
+        for rasse in rassen:
+            n = conn.execute(
+                "SELECT COUNT(DISTINCT user_id) AS cnt FROM dogs "
+                "WHERE user_id != ? AND rasse = ?",
+                (uid, rasse)
+            ).fetchone()["cnt"]
+            if n > 0:
+                rassen_detail.append({"rasse": rasse, "count": n})
+
+        rassen_detail.sort(key=lambda x: -x["count"])
+
+    # Forum-Suche-Link für die häufigste Rasse
+    forum_query = rassen_detail[0]["rasse"] if rassen_detail else None
+
+    return {
+        "count": count,
+        "rassen": rassen_detail,
+        "forum_query": forum_query,
+    }