W2 of the oak task list. A pure menu model (nesting, disabled items,
separators, checked state, wrap-around keyboard navigation arithmetic) feeds
two views: a MenuBar with drop-down popups and a right-click ContextMenu,
both built on anchored+deferred with keyboard navigation (up/down/enter/
escape), hover-opened submenus, check marks, shortcut labels and request
events. The Modal framework provides the mask, title bar, content slot and
button row with escape/enter defaults; message_box (info/warning/error),
progress_dialog (driven by ProgressContent) and file_dialog (native gpui
fallback - the fork has no prompt_for_paths platform API) are built on it.
A menus_dialogs example demonstrates everything. 79 tests pass.
Adds a parameter-panel example (cargo run -p gpui_widgets --example controls)
that demonstrates every form control: float/rational/angle sliders with
keying diamonds, a spinbox, a combo box, checkboxes, a radio group, a color
picker and a curve editor, printing each edit as a request event. Marks all
W1 checklist items done in docs/zh/oak-app-rewrite.md. 65 tests pass.
Mike-Solar