fix(macos): restore native window tiling menu (Fill/Center/Move & Resize) (#344)

The Window submenu was built without Tauri's reserved WINDOW_SUBMENU_ID
and called set_as_windows_menu_for_nsapp() manually before the menu was
attached to the app and before init_for_nsapp() ran, so NSApp.windowsMenu
never got wired up correctly. Tagging the submenu with WINDOW_SUBMENU_ID
lets Tauri's own set_menu() call set_as_windows_menu_for_nsapp() at the
right point in the lifecycle, matching the pattern in Menu::default().

Without this, macOS never auto-populated the Window menu at all (not
even the basic Minimize/Zoom items), so the Sequoia+ tiling commands
(Fill, Center, Move & Resize) and their global shortcuts were missing.

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>