feat(calls): in-app denoise tester to audition models + calibrate gate

The previous "Test Microphone" meter only showed a raw 0-100% level bar — it
never ran the gate or any model, and its scale wasn't dBFS, so it couldn't tell
you which threshold to pick or let you hear the models solo. Replace it with a
real tester that reuses the shipped worklets (/public/element-call/denoise/) in
a main-app AudioContext, mirroring the call pipeline (source -> gate -> model).

- denoisePipeline.ts: shared loader for the RNNoise/Speex flat worklets and the
  DTLN @workadventure helper, the noise gate, and a dBFS RMS meter helper.
- DenoiseTester.tsx:
  - Live monitor: hear yourself through the selected model (+gate) in real time
    (headphones) with In/Out dBFS meters and a threshold marker on the In meter
    so the gate value is meaningful to calibrate.
  - Record & compare: capture a short clip, then A/B the same audio Raw vs
    RNNoise vs Speex vs DTLN.
- Wire it into the ML settings block; remove the old raw-only MicMeter. Use real
  TDS tokens (--accent-*, --border-color, --bg-card) instead of the invented
  --lt-* names + hardcoded hex the old meter used.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/settings/general/General.tsx

@@ -75,6 +75,7 @@ import { SequenceCardStyle } from '../styles.css';
 import { useTauriUpdater } from '../../../hooks/useTauriUpdater';
 import { useDateFormatItems } from '../../../hooks/useDateFormat';
 import { playCallJoinSound } from '../../../utils/callSounds';
+import { DenoiseTester } from './DenoiseTester';
 
 type ThemeSelectorProps = {
   themeNames: Record<string, string>;
@@ -1203,91 +1204,6 @@ function useKeyBind(setter: (code: string) => void) {
 const keyLabel = (code: string) =>
   code === 'Space' ? 'Space' : code.replace('Key', '').replace('Digit', '');
 
-function MicMeter() {
-  const [level, setLevel] = useState(0);
-  const [active, setActive] = useState(false);
-  const streamRef = useRef<MediaStream | null>(null);
-  const ctxRef = useRef<AudioContext | null>(null);
-  const rafRef = useRef<number | null>(null);
-
-  const stop = useCallback(() => {
-    if (rafRef.current !== null) cancelAnimationFrame(rafRef.current);
-    rafRef.current = null;
-    streamRef.current?.getTracks().forEach((t) => t.stop());
-    streamRef.current = null;
-    ctxRef.current?.close();
-    ctxRef.current = null;
-    setActive(false);
-    setLevel(0);
-  }, []);
-
-  const start = async () => {
-    try {
-      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
-      streamRef.current = stream;
-      const ctx = new AudioContext();
-      ctxRef.current = ctx;
-      const source = ctx.createMediaStreamSource(stream);
-      const analyser = ctx.createAnalyser();
-      analyser.fftSize = 256;
-      source.connect(analyser);
-
-      const buffer = new Uint8Array(analyser.frequencyBinCount);
-      const update = () => {
-        analyser.getByteFrequencyData(buffer);
-        let sum = 0;
-        for (let i = 0; i < buffer.length; i += 1) sum += buffer[i];
-        setLevel(sum / buffer.length);
-        rafRef.current = requestAnimationFrame(update);
-      };
-      update();
-      setActive(true);
-    } catch (e) {
-      // eslint-disable-next-line no-console
-      console.error('Mic test failed', e);
-    }
-  };
-
-  useEffect(() => () => stop(), [stop]);
-
-  return (
-    <Box direction="Column" gap="100" style={{ padding: '8px 0' }}>
-      <Box direction="Row" gap="200" alignItems="Center">
-        <Button size="300" variant="Secondary" outlined onClick={active ? stop : start}>
-          <Text size="T300">{active ? 'Stop Test' : 'Test Microphone'}</Text>
-        </Button>
-        <Box
-          grow="Yes"
-          style={{
-            height: '10px',
-            background: 'var(--lt-bg-card, rgba(0,0,0,0.2))',
-            borderRadius: '5px',
-            overflow: 'hidden',
-            position: 'relative',
-            border: '1px solid var(--lt-border-color)',
-          }}
-        >
-          <Box
-            style={{
-              position: 'absolute',
-              top: 0,
-              left: 0,
-              bottom: 0,
-              width: `${Math.min(100, (level / 128) * 100)}%`,
-              background: 'var(--lt-accent-green, #00FF88)',
-              transition: 'width 0.05s linear',
-              boxShadow: '0 0 8px var(--lt-accent-green)',
-            }}
-          />
-        </Box>
-      </Box>
-      <Text size="T200" priority="300">
-        The green bar shows your live volume. Use this to tune the Gate Threshold.
-      </Text>
-    </Box>
-  );
-}
-
 function Calls() {
   const [cameraOnJoin, setCameraOnJoin] = useSetting(settingsAtom, 'cameraOnJoin');
   const [callNoiseSuppression, setCallNoiseSuppression] = useSetting(
@@ -1480,11 +1396,28 @@ function Calls() {
                   step="1"
                   value={callDenoiseGateThreshold}
                   onChange={(e) => setCallDenoiseGateThreshold(parseInt(e.target.value, 10))}
-                  style={{ width: '100%', accentColor: 'var(--lt-accent-orange)' }}
+                  style={{ width: '100%', accentColor: 'var(--accent-orange)' }}
                 />
-                <MicMeter />
               </Box>
             )}
+
+            <Box
+              direction="Column"
+              gap="200"
+              style={{ paddingTop: '8px', borderTop: '1px solid var(--border-color)' }}
+            >
+              <Text size="L400">Test &amp; calibrate</Text>
+              <Text size="T200" priority="300">
+                Audition the selected model and tune the gate without joining a call. Changes to the
+                settings above apply the next time you start a monitor or play a clip.
+              </Text>
+              <DenoiseTester
+                model={callDenoiseModel}
+                useGate={callDenoiseGate}
+                gateThreshold={callDenoiseGateThreshold}
+                nativeNS={callDenoiseNativeNS}
+              />
+            </Box>
           </Box>
         )}
       </SequenceCard>