Feature: Abo-Kündigung + Ablaufdatum + Dog-Auswahl nach Downgrade (SW by-v945)

backend/routes/admin.py

@@ -1138,9 +1138,12 @@ async def fulfill_upgrade_request(req_id: int, user=Depends(require_admin)):
             raise HTTPException(400, "Bereits erledigt.")
         if req["tier"] not in _VALID_TIERS:
             raise HTTPException(400, "Ungültiger Tier.")
+        from datetime import timedelta
+        expires_at = (datetime.now(_TZ) + timedelta(days=365)).strftime('%Y-%m-%dT%H:%M:%SZ')
         conn.execute(
-            "UPDATE users SET subscription_tier=? WHERE id=?",
-            (req["tier"], req["user_id"])
+            """UPDATE users SET subscription_tier=?, subscription_expires_at=?,
+               subscription_cancelled_at=NULL WHERE id=?""",
+            (req["tier"], expires_at, req["user_id"])
         )
         conn.execute(
             "UPDATE upgrade_requests SET fulfilled_at=strftime('%Y-%m-%dT%H:%M:%fZ','now'), fulfilled_by=? WHERE id=?",