feat(api_hooks): add /api/warmup_status and /api/warmup_wait endpoints (sub-track 3)

Sub-track 3 of startup_speedup_20260606. Builds on the Phase 7 minimal
work at b464d1fe which only added warmup_status to /api/gui/diagnostics.

New dedicated endpoints:
- GET /api/warmup_status -> controller.warmup_status() (cheap, lock-guarded)
- GET /api/warmup_wait?timeout=N -> controller.wait_for_warmup(timeout)
  then returns the final status. Default 30s.

Both callable from external clients via ApiHookClient.get_warmup_status()
and ApiHookClient.get_warmup_wait(timeout=30.0).

7 new tests in tests/test_api_hooks_warmup.py (5 unit + 2 live_gui).
All 7 pass.

src/api_hook_client.py

@@ -301,6 +301,23 @@ class ApiHookClient:
   """
   return self._make_request('GET', '/api/performance') or {}
 
+ def get_warmup_status(self) -> dict[str, Any]:
+  """
+  Returns the current warmup status: {pending, completed, failed}.
+  [C: tests/test_api_hooks_warmup.py:test_get_warmup_status_calls_correct_endpoint, tests/test_api_hooks_warmup.py:test_get_warmup_status_handles_empty_response, tests/test_api_hooks_warmup.py:test_live_warmup_status_endpoint]
+  """
+  return self._make_request('GET', '/api/warmup_status') or {}
+
+ def get_warmup_wait(self, timeout: float = 30.0) -> dict[str, Any]:
+  """
+  Blocks server-side up to `timeout` seconds waiting for the warmup to
+  complete, then returns the final status. Useful for external clients
+  that need to wait until the system is fully ready before issuing AI
+  requests.
+  [C: tests/test_api_hooks_warmup.py:test_get_warmup_wait_passes_timeout_as_query_string, tests/test_api_hooks_warmup.py:test_get_warmup_wait_uses_default_timeout_when_unspecified, tests/test_api_hooks_warmup.py:test_get_warmup_wait_handles_empty_response, tests/test_api_hooks_warmup.py:test_live_warmup_wait_endpoint_completes]
+  """
+  return self._make_request('GET', f'/api/warmup_wait?timeout={timeout}') or {}
+
 #endregion: Diagnostics
 
 #region: Project

src/api_hooks.py

@@ -321,6 +321,49 @@ class HookHandler(BaseHTTPRequestHandler):
      queue = _get_app_attr(app, "_api_event_queue")
      if queue: queue_size = len(queue)
     self.wfile.write(json.dumps({"threads": threads, "event_queue_size": queue_size}).encode("utf-8"))
+   elif self.path == "/api/warmup_status" or self.path.startswith("/api/warmup_status?"):
+    # Cheap snapshot of the AppController's warmup progress.
+    # Thread-safe: WarmupManager.status() returns a lock-guarded copy.
+    self.send_response(200)
+    self.send_header("Content-Type", "application/json")
+    self.end_headers()
+    controller = _get_app_attr(app, "controller", None)
+    if controller and hasattr(controller, "warmup_status"):
+     try:
+      payload = controller.warmup_status()
+     except Exception:
+      payload = {"pending": [], "completed": [], "failed": []}
+    else:
+     payload = {"pending": [], "completed": [], "failed": []}
+    self.wfile.write(json.dumps(payload).encode("utf-8"))
+   elif self.path == "/api/warmup_wait" or self.path.startswith("/api/warmup_wait?"):
+    # Blocks the request thread (safe under ThreadingHTTPServer) up
+    # to `timeout` seconds waiting for warmup to complete, then
+    # returns the final status. Default timeout: 30s. Useful for
+    # external clients (scripts, other tools) that need to know when
+    # the system is fully ready before issuing AI requests.
+    timeout = 30.0
+    if "?" in self.path:
+     from urllib.parse import parse_qs, urlparse
+     qs = parse_qs(urlparse(self.path).query)
+     if "timeout" in qs:
+      try: timeout = float(qs["timeout"][0])
+      except (TypeError, ValueError): timeout = 30.0
+    controller = _get_app_attr(app, "controller", None)
+    if controller and hasattr(controller, "wait_for_warmup"):
+     try:
+      controller.wait_for_warmup(timeout=timeout)
+     except Exception: pass
+     try:
+      payload = controller.warmup_status()
+     except Exception:
+      payload = {"pending": [], "completed": [], "failed": []}
+    else:
+     payload = {"pending": [], "completed": [], "failed": []}
+    self.send_response(200)
+    self.send_header("Content-Type", "application/json")
+    self.end_headers()
+    self.wfile.write(json.dumps(payload).encode("utf-8"))
    else:
     self.send_response(404)
     self.end_headers()