feat(ui): replace app-menu logo with a quick-access file toolbar

Remove the OCS-logo button and the dropdown menu it opened; the top strip
now shows direct New / Open / Save / Save As / Print buttons ahead of the
undo/redo controls. Drop the HELP and OPTIONS commands (HELP dumped text to
the command line, OPTIONS aliased the drafting-settings popup).

The app-menu overlay is gone, so its rendering code, MENU_ITEMS, four dead
messages, and the LOGO_RED / GEAR / HELP assets are removed. The recents
list it held is the only survivor — moved into OpenCADStudio.recent_files
via a new app/recent.rs, backing the Start page's Recent Documents panel.

Quick-access icons are redrawn in a cleaner style (file-plus, folder-open,
device-floppy, file-export, printer) and tinted light so they read on the
dark strip; FOLDER / DOC keep their old glyphs for the file browser.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/view/mod.rs

@@ -1084,7 +1084,7 @@ impl OpenCADStudio {
         // Properties / layers panels carry no useful state on the Start tab.
         // Replace the properties panel with a Recent Documents list there.
         let properties_el: Element<'_, Message> = if tab.is_start {
-            recent_files_panel(&self.app_menu.recent)
+            recent_files_panel(&self.recent_files)
         } else if self.show_properties && !self.clean_screen {
             tab.properties.view()
         } else {
@@ -1304,7 +1304,6 @@ impl OpenCADStudio {
 
         let composed = stack![
             main_ui,
-            self.app_menu.view(),
             snap_layer,
             scale_layer,
             statusbar_menu_layer,