feat(lotus): report the local mic level to the host (cinny #146)

The host had only a boolean `speaking` for yourself, throttled to 500 ms, so
nothing on the call bar showed that the mic was actually picking you up.

- lotusMicLevel.ts: one shared local mic sampler (a clone of the published
  track, ~10 Hz RMS, while a mic is published, muted or not), shared per
  call view model so there is one AudioContext.
- MicLevelQuantizer: 0–3 bars (≈ −46/−36/−26 dBFS), rising at once and
  falling one bar per sample so it doesn't flicker between words.
- fromWidget io.lotus.mic_level { bars } only when the value changes; 0 while
  muted or with no mic. Opt-in with the host state stream (lotusCallState=1).
- "Talking while muted" (#37) now reads the same sampler instead of running
  its own; same gate and behaviour.

Verified in a local call with a fake-tone mic: the host receives 0–3 as the
tone rises/falls (about 4 messages/s while it changes), 0 on mute and levels
again on unmute; muted + tone still raises speakingWhileMuted and the host's
"You're muted" notice. Lotus/room suites pass on Node 22 (148 tests).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/lotus/lotusMutedSpeech.ts

@@ -6,14 +6,15 @@ Please see LICENSE in the repository root for full details.
 */
 
 import {
-  type LocalTrackPublication,
-  type Room as LivekitRoom,
-  RoomEvent,
-  Track,
-} from "livekit-client";
-import { Observable, distinctUntilChanged, switchMap } from "rxjs";
+  type Observable,
+  distinctUntilChanged,
+  map,
+  scan,
+  startWith,
+} from "rxjs";
 
 import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
+import { type LocalMicSample, observeLocalMicSample$ } from "./lotusMicLevel";
 
 /**
  * [lotus #37] "Talking while muted" detection for the LOCAL participant.
@@ -23,13 +24,12 @@ import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
  * tells the user they are talking into a muted mic. This taps a CLONE of the
  * published track (the post-processor track when the in-source denoiser is
  * active, so keyboard noise doesn't count), samples RMS at ~10 Hz and emits a
- * debounced boolean. Zero cost when unmuted (tap torn down), local-only —
+ * debounced boolean. Local-only —
  * the flag rides `io.lotus.call_state` to the host and never reaches other
  * participants.
  */
 
 export const MUTED_SPEECH_RMS = 0.015; // ≈ −36 dBFS; normal speech into a headset is 0.05–0.3
-const SAMPLE_MS = 100;
 const ON_SAMPLES = 3; // 300 ms of voice before we say "talking"
 const OFF_SAMPLES = 8; // 800 ms of quiet before we drop it
 
@@ -61,94 +61,24 @@ export class MutedSpeechGate {
   }
 }
 
-const mutedMicTrack = (room: LivekitRoom): MediaStreamTrack | null => {
-  const pub: LocalTrackPublication | undefined =
-    room.localParticipant.getTrackPublication(Track.Source.Microphone);
-  const track = pub?.track?.mediaStreamTrack;
-  return pub?.isMuted && track && track.readyState === "live" ? track : null;
-};
-
 /**
  * Emits while the local mic is muted and voice is detected on it. Emits
  * `false` whenever the mic is unmuted, unpublished or the connection changes.
+ * [lotus #146] Fed by the shared local mic sampler (lotusMicLevel.ts), which
+ * also drives the host's mic level meter while unmuted.
  */
 export function observeSpeakingWhileMuted$(
   vm: CallViewModel,
 ): Observable<boolean> {
-  return vm.allConnections$.pipe(
-    switchMap(
-      (data) =>
-        new Observable<boolean>((subscriber) => {
-          const rooms = data.getConnections().map((c) => c.livekitRoom);
-          let ctx: AudioContext | null = null;
-          let clone: MediaStreamTrack | null = null;
-          let timer: ReturnType<typeof setInterval> | undefined;
-          let tapped: MediaStreamTrack | null = null;
-
-          const stopTap = (): void => {
-            if (timer !== undefined) clearInterval(timer);
-            timer = undefined;
-            clone?.stop();
-            clone = null;
-            void ctx?.close().catch(() => undefined);
-            ctx = null;
-            tapped = null;
-            subscriber.next(false);
-          };
-
-          const startTap = (source: MediaStreamTrack): void => {
-            try {
-              clone = source.clone();
-              clone.enabled = true; // the source is disabled by the mute — the clone must not be
-              ctx = new AudioContext();
-              const analyser = ctx.createAnalyser();
-              analyser.fftSize = 1024;
-              ctx
-                .createMediaStreamSource(new MediaStream([clone]))
-                .connect(analyser);
-              const buf = new Float32Array(analyser.fftSize);
-              const gate = new MutedSpeechGate();
-              tapped = source;
-              timer = setInterval(() => {
-                analyser.getFloatTimeDomainData(buf);
-                let sum = 0;
-                for (let i = 0; i < buf.length; i += 1) sum += buf[i] * buf[i];
-                subscriber.next(gate.push(Math.sqrt(sum / buf.length)));
-              }, SAMPLE_MS);
-            } catch {
-              stopTap();
-            }
-          };
-
-          const reconcile = (): void => {
-            const track =
-              rooms.map(mutedMicTrack).find((t) => t !== null) ?? null;
-            if (track === tapped) return;
-            if (tapped) stopTap();
-            if (track) startTap(track);
-          };
-
-          const events = [
-            RoomEvent.TrackMuted,
-            RoomEvent.TrackUnmuted,
-            RoomEvent.LocalTrackPublished,
-            RoomEvent.LocalTrackUnpublished,
-            RoomEvent.Reconnected,
-            RoomEvent.Disconnected,
-          ] as const;
-          rooms.forEach((room) =>
-            events.forEach((ev) => room.on(ev, reconcile)),
-          );
-          subscriber.next(false);
-          reconcile();
-          return () => {
-            rooms.forEach((room) =>
-              events.forEach((ev) => room.off(ev, reconcile)),
-            );
-            if (tapped) stopTap();
-          };
-        }),
-    ),
+  return observeLocalMicSample$(vm).pipe(
+    scan((gate: MutedSpeechGate | null, sample: LocalMicSample | null) => {
+      if (!sample?.muted) return null;
+      const g = gate ?? new MutedSpeechGate();
+      g.push(sample.rms);
+      return g;
+    }, null),
+    map((gate) => gate?.value ?? false),
+    startWith(false),
     distinctUntilChanged(),
   );
 }