UiSlider takes v-model, min, max, step and disabled
over Core's native range input, emits numbers, and with `hold` never
rewrites a focused handle and takes the model back on blur. It is a
functional render function, so the portable style parameter rows use it
too. The Display, Radio, RTL-SDR, Cockpit, mission replay and style
parameter sliders render with it; server-rendered markup keeps their
default values.
The Radio panel's and Cockpit's Enable, launcher, station tag,
transport and volume controls call RadioControls through the radio
store instead of DOM listeners. A refused station tag gets the kept tag
back from act(), which now returns what the answering action returned.
The Cockpit's station steps keep rotate: false. The unused element
fields go from the shell.