test(app_controller_sigint): update _FakeController for Phase 6 Result-based helpers

The Phase 6 Group 6.1 migration changed _install_sigint_exit_handler
to call controller._install_signal_handler_result(handler) and
controller._shutdown_io_pool_result(). The _FakeController test stub
needs to provide these new helpers to maintain the test contract.

tests/test_app_controller_sigint.py

@@ -49,12 +49,38 @@ def restore_sigint():
 
 
 class _FakeController:
- """Minimal stand-in for AppController: just exposes _io_pool."""
+ """Minimal stand-in for AppController: just exposes _io_pool + the
+ Result-based signal-handler helpers added in Phase 6 Group 6.1."""
 
  def __init__(self) -> None:
   self._io_pool = ThreadPoolExecutor(
    max_workers=2, thread_name_prefix="fake-ctrl"
   )
+  self._signal_handler_error = None
+
+ def _shutdown_io_pool_result(self):
+  """Phase 6 Group 6.1 helper (Result-based)."""
+  from src.result_types import OK, ErrorInfo, ErrorKind, Result
+  try:
+   self._io_pool.shutdown(wait=False)
+   return OK
+  except Exception as e:
+   return Result(data=None, errors=[ErrorInfo(
+    kind=ErrorKind.INTERNAL, message=str(e),
+    source="app_controller._shutdown_io_pool_result", original=e,
+   )])
+
+ def _install_signal_handler_result(self, handler):
+  """Phase 6 Group 6.1 helper (Result-based)."""
+  from src.result_types import OK, ErrorInfo, ErrorKind, Result
+  try:
+   signal.signal(signal.SIGINT, handler)
+   return OK
+  except Exception as e:
+   return Result(data=None, errors=[ErrorInfo(
+    kind=ErrorKind.INTERNAL, message=str(e),
+    source="app_controller._install_signal_handler_result", original=e,
+   )])
 
 
 def test_install_sigint_handler_installs_callable(restore_sigint: Any) -> None: