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/mcp.rs

@@ -68,6 +68,7 @@ const READ_OPS: &[&str] = &[
     "audit",
     "text_search",
     "text_audit",
+    "keytips",
     "capture",
 ];
 const EXECUTE_OPS: &[&str] = &[