Ribbon key tips: Alt shows codes on tabs, buttons and menu items

A lone Alt shows a code on every ribbon tab and quick-access button.
Typing a tab code opens the tab and shows the codes of its buttons,
dropdowns, slide-outs and collapsed panels; a button code runs it, a
dropdown or slide-out code opens it and shows its item codes, Esc goes
back one level. Codes follow the reference ribbon; buttons without a
reference counterpart get none and unnamed menu items are numbered.

Codes are drawn as accent pills over the widgets that reported their
bounds in the current frame, with a hint bar under the ribbon. While
the tips are open keys go to them only. The automation gets a keytips
action and read operation.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/control/mod.rs

@@ -559,6 +559,7 @@ impl OpenCADStudio {
                 | "audit"
                 | "text_search"
                 | "text_audit"
+                | "keytips"
         );
         if !query && !self.control.enabled {
             return (
@@ -850,6 +851,7 @@ impl OpenCADStudio {
                     }
                 }
                 "grips" => self.control_grips(),
+                "keytips" => self.ribbon.keytips_json(req["detail"].as_str() == Some("full")),
                 "xdata_get" => self.xdata_read(&req),
                 "get_selection" => self.control_get_selection(),
                 "text_search" => self.control_text_search(&req).unwrap_or_else(|e| e),