Keep the Radio tuning dial silent unless a stream is playing

Releasing the tuning dial always started the chosen station, plus tuning
static, even when nothing was playing. It now follows the Previous/Next
rule: the release plays only if a stream was loading, buffering or playing
when the drag began; otherwise it just selects the station.

The privacy note no longer lists finishing tuning as a way to connect and
now names voice instead, in all locales. Docs, changelog and comments are
tightened to match.

src/testSupport/radioLayerHarness.mjs

@@ -1,7 +1,5 @@
-/** Shared Radio layer test stand-ins: a station row, fake Audio, directory fetch and viewer. */
 import { radioLayer } from '../data/radio.js';
 
-/** One accepted Radio Browser directory row. */
 export function radioStationRow(overrides = {}) {
   return {
     id: '00000000-0000-4000-8000-000000000001',