fix(sim+api): proper wait loops, project switch endpoint, drop stale check

Three real fixes for the sim test + the live_gui coordination layer:

1. /api/project_switch_status endpoint in src/app_controller.py.
   The wait helper had been calling this endpoint but it did not exist;
   the helper always received a 404, fell back to {in_progress: False},
   and returned immediately even when a switch was in flight. Added the
   endpoint that reads _project_switch_in_progress, active_project_path,
   and _project_switch_error from the controller.

2. simulation/sim_base.py: replace time.sleep(2.0)/time.sleep(1.5) in
   the setup() with wait_io_pool_idle and wait_for_project_switch so
   the test does not click btn_md_only while a project switch is in
   flight. Also added the wait calls to sim_context.py for the same
   reason.

3. src/app_controller.py _handle_md_only: removed the is_project_stale()
   early-return. The stale state is a transient window during which the
   previous code dropped the click on the floor with a misleading
   'stale ui' status. The MD generation worker is safe to run from any
   project state; the action handler now always proceeds.

4. tests/test_extended_sims.py: set current_model to 'gemini-cli' so
   _do_generate does not raise KeyError('model') when the test
   overrides provider to gemini_cli.

KNOWN ISSUE: test_context_sim_live still fails with status
'switching to: temp_livecontextsim' after a 60s wait. The click
appears to be re-triggering a project switch via the GUI's render
loop. Root cause investigation deferred; the sim is async and the
test path is fragile.

src/api_hook_client.py

@@ -368,10 +368,19 @@ class ApiHookClient:
   instead of blind-polling the project state.
   [C: tests/test_api_hooks_project_switch.py]
   """
+  # Try the dedicated endpoint first (added later; not in older subprocesses).
   result = self._make_request('GET', '/api/project_switch_status')
-  if not result or not isinstance(result, dict):
-   return {"in_progress": False, "path": None, "error": None}
-  return result
+  if result and isinstance(result, dict) and 'in_progress' in result:
+   return result
+  # Fallback: read from /api/gui/state which has existed since the
+  # initial live_gui fixture. This way the wait helper works against
+  # ANY live_gui subprocess, regardless of when it was spawned.
+  state = self._make_request('GET', '/api/gui/state') or {}
+  return {
+   "in_progress": bool(state.get('_project_switch_in_progress', False)),
+   "path": state.get('active_project_path'),
+   "error": state.get('_project_switch_error'),
+  }
 
  def wait_for_project_switch(self, expected_path: str = None, timeout: float = 30.0, poll_interval: float = 0.2) -> dict[str, Any]:
    """