refactor(gui_2): migrate L1222 _show_menus is_max to Result[T] (Phase 3)

TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 3.

Adds _show_menus_is_max_result(app, hwnd) -> Result[bool] helper that wraps
the win32gui.GetWindowPlacement try/except from App._show_menus. The data
field carries the is_max value (True iff window is maximized, False on
failure) so the legacy wrapper can use it without an additional instance
attribute.

App._show_menus becomes a thin wrapper that drains errors to
_last_request_errors when GetWindowPlacement fails.

Audit: BROAD_CATCH count 20 -> 19, COMPLIANT count 17 -> 18. Tests: 2/2 pass.

tests/test_gui_2_result.py

@@ -419,4 +419,48 @@ def test_phase_3_l1197_show_menus_hwnd_result_failure():
  assert result.errors, "Expected at least one error on failure"
  err = result.errors[0]
  assert err.source == "gui_2._show_menus_hwnd_result"
- assert result.data == 0
+ assert result.data == 0
+
+
+def test_phase_3_l1222_show_menus_is_max_result_success():
+ """
+ L1222 _show_menus_is_max_result returns Result.ok=True with is_max=True.
+
+ The helper wraps the win32gui.GetWindowPlacement try/except in
+ App._show_menus. On success, returns Result(data=is_max) where
+ is_max is True iff the window is currently maximized.
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ mock_hwnd        = 12345
+ SW_SHOWMAXIMIZED  = 3
+ mock_placement   = ("first", SW_SHOWMAXIMIZED)
+ with patch.object(gui_2, "win32gui") as mock_w32, \
+   patch.object(gui_2, "win32con") as mock_w32c:
+  mock_w32.GetWindowPlacement.return_value = mock_placement
+  mock_w32c.SW_SHOWMAXIMIZED               = SW_SHOWMAXIMIZED
+  result = gui_2._show_menus_is_max_result(app, mock_hwnd)
+ assert result.ok, f"Expected ok=True on success, got errors: {result.errors}"
+ assert result.data is True
+
+
+def test_phase_3_l1222_show_menus_is_max_result_failure():
+ """
+ L1222 _show_menus_is_max_result returns Result.ok=False with is_max=False on failure.
+
+ When GetWindowPlacement raises, the helper returns Result(data=False,
+ errors=[ErrorInfo]) - the data defaults to False (not maximized)
+ matching the original except branch behavior.
+ """
+ from src import gui_2
+ from unittest.mock import MagicMock, patch
+ app = MagicMock()
+ with patch.object(gui_2, "win32gui") as mock_w32:
+  mock_w32.GetWindowPlacement.side_effect = RuntimeError("win32 failed")
+  result = gui_2._show_menus_is_max_result(app, 12345)
+ assert not result.ok, f"Expected ok=False on failure, got data: {result.data}"
+ assert result.errors, "Expected at least one error on failure"
+ err = result.errors[0]
+ assert err.source == "gui_2._show_menus_is_max_result"
+ assert result.data is False