feat(audio-rooms): M1 listener-only wire-up — Connect button + Connected chip + mute

Wires `connectNestsListener` into the existing NIP-53 audio-room "stage" so
a user can tap Connect, see the live connection state, and hear hosts
speaking. Per the audio-rooms completion plan
(`nestsClient/plans/2026-04-26-audio-rooms-completion.md`) phase M1.

UI (amethyst):
- AudioRoomStage gets a state-chip / Connect / Disconnect / Mute row
  above the existing hand-raise. State chip walks ResolvingRoom →
  OpeningTransport → MoQ-handshake → Connected; Failed surfaces the
  reason inline with a Retry button. The 30312 `service` tag drives
  visibility — rooms hosted on non-nests servers show "Audio not
  available" and the rest of the stage UI continues to work.

ViewModel (commons):
- New `AudioRoomViewModel` in commons/.../viewmodels/ owns one
  `NestsListener` and one `AudioRoomPlayer` per active speaker, exposes
  a single `StateFlow<AudioRoomUiState>`, and reconciles subscriptions
  whenever the screen pushes a new speaker set via `updateSpeakers`.
  Audio-pipeline construction is injected via `decoderFactory` /
  `playerFactory` so a future desktop port can reuse the orchestration
  once Compose Desktop has WebTransport. Unit-tested with a fake
  `NestsListenerConnector` driving state transitions directly.

nestsClient:
- `AudioPlayer.setMuted(Boolean)` joins the interface; `AudioTrackPlayer`
  routes it through `AudioTrack.setVolume(0f/1f)`. Mute keeps the
  decode + network pipeline running so unmute is sample-accurate.

Build:
- `:commons` commonMain now `implementation(project(":nestsClient"))` so
  the shared VM can see `NestsListener` / `AudioRoomPlayer` / interfaces.
  Concrete OkHttp / Quic / MediaCodec / AudioTrack actuals stay in
  `:nestsClient`'s platform source sets and are bound by an
  Android-side `AudioRoomViewModelFactory` co-located with the screen.

Verified: `./gradlew spotlessApply :commons:jvmTest :nestsClient:jvmTest
:quic:jvmTest :amethyst:compilePlayDebugKotlin` all green.

nestsClient/src/commonTest/kotlin/com/vitorpamplona/nestsclient/audio/AudioRoomPlayerTest.kt

@@ -206,6 +206,8 @@ class AudioRoomPlayerTest {
             private set
         val stopped: Boolean get() = stopCount > 0
         val queued = mutableListOf<ShortArray>()
+        var muted: Boolean = false
+            private set
 
         override fun start() {
             started = true
@@ -215,6 +217,10 @@ class AudioRoomPlayerTest {
             queued.add(pcm)
         }
 
+        override fun setMuted(muted: Boolean) {
+            this.muted = muted
+        }
+
         override fun stop() {
             stopCount++
         }