v0.90.1: ListToolbar select sizing and menu-facet disclosure/a11y fixes

Three fixes inside ListToolbar, all surfaced by a fresh-context coherence read of a consumer's Members screen. No consumer action is required.

Fixed

• ListToolbar's 'select' facet no longer pins to daisyUI's own fixed 320px clamp (width: clamp(3rem, 20rem, 100%), whose middle value is a fixed length, not a container-relative one); it now sizes to its own content (width: auto; max-width: 100%), so a short-option facet renders narrow and a container of real-world facets (four selects plus a menu facet plus search) fits one line at the widths the Members-refinement recomposition targeted. A select facet's border also now shares the 'menu' facet's own var(--cairn-card-border) treatment (via the same --input-color custom property daisy's compiled rule already reads), so the two read as one control family rather than two vocabularies side by side.
• A 'menu' facet's option list and the overflow disclosure's own panel no longer open on keyboard focus alone: daisyUI's .dropdown shows .dropdown-content on :focus-within for free, which let Tabbing onto a trigger reveal the panel while aria-expanded (driven purely by this component's own dropdown-open class) stayed false. Both disclosures' visibility now tracks dropdown-open exactly, so aria-expanded always matches what is actually shown.
• A 'menu' facet's option list carries real ARIA menu semantics (role="menu" with role="menuitemradio" options, previously bare buttons in a plain <ul>): the applied value is exposed programmatically via aria-checked, not just the sighted-only check glyph, and a roving tabindex makes only the focused option a Tab stop, with ArrowUp/ArrowDown/Home/End moving that focus, wrapping at the ends, mirroring the segmented filter's own keyboard model. Escape-closes-and-returns-focus and the click-to-select behavior are unchanged.