Action Hotkey Tile

Server component, no hooks: the tile is an ordinary semantic <button type="button">, so focus and keyboard activation work without a single line of JS. The keyboard shortcut is duplicated twice — as a visual pill of separate <kbd> elements in the corner and as the aria-keyshortcuts attribute on the button itself; the pill as a whole is marked aria-hidden, because a screen reader already announces the combination from the attribute, and reading characters such as "Ctrl" out letter by letter again would be noise on top of the action name. The icon is switched through icon (search, add, command), and the icon tile's colour through tone by the category-wide "background and glyph from one hue" formula. The description is hidden on a narrow container through @container, while the title always remains. The palette has been moved to light-dark(): in the dark branch the border and the keys are lighter than the background rather than darker. The button has no surface by default — it is set by the background prop, and then the theme branch is computed from the lightness of the given colour.