- Selections take the playback fallback as a `playFallback` option and
set it after releasing a stale stream, instead of callers arming state
that the release then had to save and restore.
- Move the tuner `station-unavailable` release and the Pause label while
a stream connects out of this branch: both were wrong on main already
and go in a separate change.
- Share the Radio layer test setup in src/testSupport/radioLayerHarness.mjs
and fold overlapping Next/Previous tests (13 to 7).
- One-line comments and a two-line changelog entry.