feat(ui): classic pull-down menu bar and ribbon toggle

MENUBAR 1 shows File, Edit, View, Insert, Format, Tools, Draw,
Dimension, Modify, Parametric and Help menus above the ribbon; every
entry runs an existing command, and a test keeps each entry pointing at
a registered command. RIBBONCLOSE hides the ribbon and RIBBON brings it
back, so the menus can replace it. Both choices persist.

Also translates the "File" label, which every locale had left in
English.

Refs #1450

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/settings.rs

@@ -400,6 +400,10 @@ pub struct UserSettings {
     pub pick_box: i32,
     /// HPASSOC: new hatches follow their boundary objects.
     pub hatch_associative: bool,
+    /// MENUBAR: the classic pull-down menus show above the ribbon.
+    pub show_menu_bar: bool,
+    /// RIBBONCLOSE hid the ribbon; RIBBON brings it back.
+    pub ribbon_closed: bool,
     /// When true, double-clicking a block reference starts REFEDIT instead of BEDIT.
     pub double_click_block_refedit: bool,
     /// When true, double-clicking a block with attributes opens ATTEDIT.
@@ -834,6 +838,8 @@ impl Default for UserSettings {
             cursor_size: 5,
             pick_box: 3,
             hatch_associative: true,
+            show_menu_bar: false,
+            ribbon_closed: false,
             options_tab: crate::ui::window::options::OptionsTab::General,
             show_viewcube: true,
             show_ucs_icon: true,