feat(warmup): per-module canary records (thread + timing observability)

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.

tests/test_api_hooks_warmup.py

@@ -84,3 +84,42 @@ def test_live_warmup_wait_endpoint_completes(live_gui) -> None:
  # In a live session the warmup either already finished (no pending) or
  # completed within the 2s window. Either way the response is well-formed.
  assert isinstance(result["pending"], list)
+
+def test_get_warmup_canaries_calls_correct_endpoint() -> None:
+ """get_warmup_canaries() hits GET /api/warmup_canaries and unwraps the list."""
+ client = ApiHookClient()
+ with patch.object(client, "_make_request") as mock_make:
+  mock_make.return_value = {"canaries": [{"canary_id": 1, "module": "os", "thread_name": "controller-io-0", "thread_id": 12345, "status": "completed"}]}
+  result = client.get_warmup_canaries()
+  assert isinstance(result, list)
+  assert len(result) == 1
+  assert result[0]["module"] == "os"
+  assert result[0]["status"] == "completed"
+  mock_make.assert_called_once_with("GET", "/api/warmup_canaries")
+
+
+def test_get_warmup_canaries_handles_empty_response() -> None:
+ """get_warmup_canaries() returns [] when server returns None or empty payload."""
+ client = ApiHookClient()
+ with patch.object(client, "_make_request") as mock_make:
+  mock_make.return_value = None
+  result = client.get_warmup_canaries()
+  assert result == []
+
+
+def test_live_warmup_canaries_endpoint(live_gui) -> None:
+ """Live: GET /api/warmup_canaries returns canary records with thread + status info."""
+ client = ApiHookClient()
+ assert client.wait_for_server(timeout=10)
+ canaries = client.get_warmup_canaries()
+ assert isinstance(canaries, list)
+ assert len(canaries) >= 1, "expected at least one canary record from live warmup"
+ for c in canaries:
+  assert "canary_id" in c
+  assert "module" in c
+  assert "thread_name" in c
+  assert "thread_id" in c
+  assert "status" in c
+  assert c["status"] in ("running", "completed", "failed", "cancelled")
+ completed = [c for c in canaries if c["status"] == "completed"]
+ assert len(completed) >= 1, "at least one canary should be completed"