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/commands/display.rs

@@ -154,9 +154,9 @@ impl OpenCADStudio {
             "POLAR" => {
                 return Some(Task::done(Message::TogglePolar));
             }
-            // DSETTINGS / OSNAP / OPTIONS — open the drafting-settings popup, which
-            // is OCS's settings surface (the persisted DYN/ORTHO/POLAR/OSNAP prefs).
-            "DSETTINGS" | "OSNAP" | "OPTIONS" | "OP" => {
+            // DSETTINGS / OSNAP — open the drafting-settings popup, which is OCS's
+            // settings surface (the persisted DYN/ORTHO/POLAR/OSNAP prefs).
+            "DSETTINGS" | "OSNAP" => {
                 return Some(Task::done(Message::ToggleSnapPopup));
             }
             // UNITS — open the drawing-units picker (linear / angular format).