Fix [m] menu keybindings not working on macOS

[abaj8494]

Problem

On macOS, [m]-prefixed menu keybindings (e.g. [m]control_menu(down) <C-n>) silently fail. Ctrl+key combos like Ctrl+N and Ctrl+P never reach MyLineEdit::keyPressEvent because macOS's Cocoa text input system intercepts them first — NSTextField's key binding mechanism maps Ctrl+N to moveDown:, Ctrl+P to moveUp:, etc., consuming the event before Qt can dispatch it.

Root cause

Two issues:

1. Cocoa eats Ctrl+key events in text fields. The Cocoa input handling layer processes these combos at the NSView level, so Qt never generates a KeyPress event for them. However, they do arrive as QEvent::ShortcutOverride events in the BaseSelectorWidget event filter, which runs before Cocoa's text handling.

2. MyLineEdit::keyPressEvent drops found commands. When a menu command is found via get_menu_command, the handler calls event->ignore() expecting the event to bubble up to MainWidget::keyPressEvent. This doesn't work because the widget hierarchy (MyLineEdit → BaseSelectorWidget → …) doesn't guarantee propagation to MainWidget.

Fix

• Intercept ShortcutOverride events in BaseSelectorWidget::eventFilter and dispatch matching [m] menu commands directly via handle_command_types.
• In MyLineEdit::keyPressEvent, execute found menu commands immediately instead of ignoring the event.

Testing

With keys_user.config:

[m]control_menu(down);[M]screen_down <C-n>
[m]control_menu(up);[M]screen_up <C-p>

Verified on macOS (ARM64, Qt 6.11):

• Ctrl+N/P navigate up/down in search menus, bookmark lists, and open-document lists
• Ctrl+N/P scroll the page in normal view
• Backspace still works in menu search fields
• Arrow keys continue to work in all menus