fix: add missing router = APIRouter() in agent_loop_routes.py

api/agent_loop_routes.py

@@ -55,6 +55,8 @@ async def run_loop_removed():
 
 # ── SSE run-stream ────────────────────────────────────────────────────────────
 
+router = APIRouter()
+
 @router.post('/api/agent/run-stream')
 async def agent_run_stream(body: ReasonLoopIn, request: Request):
     # S-BENCH: auth guard — consistente con /api/exec e /api/execute-shell