UiSelect renders the bare native select with v-model, options and
disabled. Options that carry their own attributes come through the slot, a
caller's own change handler still reaches the select, and hold never
rewrites a focused select and takes the model back on blur. Without hold, a
select takes its model back once its change has rendered, so a pick its
owner refuses goes back, as the raw value binding did.
The HUD layout, draw colour, RTL-SDR gain, radio station tag, voice
provider, voice timeout, scene and CCTV camera selects now render through
it.