fix: satisfy lint and diff-coverage gates for admin gating

basedpyright requires _admin_tip_anchor to exist after __init__, so the
anchor is created eagerly instead of lazily. Cover the red-tip branch and
the status-bar menu gate; the menu test swaps in a QMenu subclass with a
no-op exec because PySide method lookup ignores class-attr monkeypatches.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/aare/gui/main_window.py

@@ -353,6 +353,13 @@ class MainWindow(QMainWindow):
         # after the docks), not in the left column. Always visible.
         self.beamline_state_panel = BeamlineStatePanel(staff=self._decoded_token.staff, parent=self)
 
+        # Anchor for _show_admin_tip: QToolTip inherits QSS from the widget
+        # it is shown for, so this hidden label carries the red warning wash
+        # without reddening any other tooltip. Eager, not lazy — basedpyright
+        # requires instance attributes to exist after __init__.
+        self._admin_tip_anchor = QLabel(self)
+        self._admin_tip_anchor.hide()
+
         # Beamline / Experiment as tabs (like the Dewar samples dock) instead
         # of two stacked banner groups; the pages keep their banner children.
         # documentMode: no pane frame, so the fixed-width panels aren't inset.
@@ -1477,12 +1484,8 @@ class MainWindow(QMainWindow):
 
     def _show_admin_tip(self, message: str) -> None:
         # "Not admin" denials are passive red tips, not QMessageBoxes:
-        # nothing to click away. QToolTip inherits QSS from the widget it is
-        # shown for, so a hidden anchor keeps the red wash off every other
-        # tooltip; styled at show time so it always matches the theme.
-        if not hasattr(self, "_admin_tip_anchor"):
-            self._admin_tip_anchor = QLabel(self)
-            self._admin_tip_anchor.hide()
+        # nothing to click away. Styled at show time so it always matches
+        # the theme.
         self._admin_tip_anchor.setStyleSheet(admin_tip_qss(self._theme_mode))
         QToolTip.showText(QCursor.pos(), message, self._admin_tip_anchor)