Keep Radio playback state consistent after a silent Next

Review follow-ups for HAL-722. A Next or Previous that only selects a
station now leaves nothing of the previous stream behind:

- Selecting another station without playing stops a paused or failed
  stream, so the panel, Stop, voice summaries and the audio element agree
  on "stopped". A fallback the caller armed for the new selection is kept.
- A silent UI step arms no broadcaster fallback, and a user Play of the
  selected station drops one left by a cancelled voice step. Voice steps
  pass `fallback: true` because voice starts the prepared playback later.
- A user step to another station emits a `select` playback control, and
  the realtime voice handoff treats it like Pause and Stop.
- A tuner release onto a station the directory no longer has stops the
  stream the drag paused, publishing one state with the gesture's origin,
  so the button reads PLAY and a voice handoff is cancelled.
- The transport buttons offer Pause while a stream connects, matching
  what a click does.
- The privacy note names every action that connects to a broadcaster
  (play, finishing tuning, choosing a station on the globe) in all
  locales.

The Next/Previous layer tests live in src/data/radioNextState.test.mjs.

src/ui/radioBindings.js

@@ -338,9 +338,8 @@ export function bindRadioControls() {
     const pool = this._radioTunerPool.length
       ? this._radioTunerPool
       : this._radioTunerStations;
-    // Stepping only selects until the user has pressed Play; once a stream is
-    // active it follows the selection so the old broadcaster does not keep
-    // playing under a new station label.
+    // Keep the step silent unless a stream is active. An active stream follows
+    // the selection, so the station label matches the broadcaster.
     const { audioState } = this.radio.getUIState();
     const cycled = this.radio.cycleStation(direction, {
       rotate,

src/ui/radioControls.test.mjs

@@ -182,7 +182,7 @@ test('destruction releases an active tuner pointer after revoking listeners', ()
   }
 });
 
-test('Next and Previous select without playing until playback has started', () => {
+test('Next and Previous play only while a stream is active', () => {
   const f = fixture();
   try {
     f.controls.connect();

src/ui/radioPresentation.js

@@ -20,7 +20,9 @@ export function renderRadioState(state) {
   const interactive = enabled && !transitioning && !uncertain;
   const selected = state.selected || null;
   const hasStations = state.filteredCount > 0;
-  const activePlayback = ['playing', 'buffering'].includes(state.audioState);
+  const activePlayback = ['loading', 'buffering', 'playing'].includes(
+    state.audioState,
+  );
   document
     .getElementById('title-bar')
     ?.classList.toggle('radio-broadcasting', state.audioState === 'playing');

src/ui/templates/context.html

@@ -162,7 +162,7 @@
               <a id="radio-station-homepage" href="#" target="_blank" rel="noopener noreferrer" hidden data-i18n>STATION SITE</a>
               <a href="https://www.radio-browser.info/" target="_blank" rel="noopener noreferrer" data-i18n>DIRECTORY: RADIO BROWSER</a>
             </div>
-            <p class="radio-privacy" data-i18n>Audio connects directly to the broadcaster after you press play. Your IP is visible to that broadcaster.</p>
+            <p class="radio-privacy" data-i18n>Audio connects directly to the broadcaster when you press play, finish tuning or choose a station on the globe. Your IP is visible to that broadcaster.</p>
             <div id="sdr-radio-card" class="sdr-radio-card" role="group" aria-label="Local RTL-SDR receiver" data-i18n-aria-label>
               <div class="sdr-radio-heading">
                 <strong data-i18n>LOCAL RTL-SDR</strong>