Adds a canary record for each module submitted to the warmup, tracking:
canary_id, module, thread_name, thread_id, submit_ts, start_ts,
end_ts, elapsed_ms, status, error.
Surface:
- WarmupManager.canaries() returns list[dict] (defensive copy)
- AppController.warmup_canaries() returns list[dict] (delegation)
- GET /api/warmup_canaries Hook API endpoint
- ApiHookClient.get_warmup_canaries() returns list[dict]
Example: the warmup of google.genai records a 1187ms canary on
thread controller-io_0 with thread_id 50420, canary_id 1.
11 new tests (8 unit in test_warmup_canaries + 3 in test_api_hooks_warmup).
All pass; live_gui smoke test confirms endpoint returns real data.
