feat(denoise): browser-native default, quality-ordered model picker, wire native-NS

- Model dropdown is now ordered by quality/CPU, best first (DeepFilterNet 3 →
  DTLN → RNNoise → Speex); fix RNNoise's inaccurate "High" voice-quality label.
- When a user opts into the ML tier, default to the highest-quality model
  (DeepFilterNet 3). The tier default stays browser-native (known-good, best
  perceived in testing so far).
- Wire the "Series Suppression" (native-NS-before-ML) toggle into the real call
  path — it was applied only in the settings tester, so the tester could sound
  better than the actual call. Default it OFF (a single NS stage is best
  practice; it's an opt-in test aid).
- isMLDenoiseSupported now also requires WebAssembly, so ML isn't offered on
  strict-CSP shells where it would silently fall back to the raw mic.

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

src/app/state/settings.ts

@@ -236,9 +236,13 @@ const defaultSettings: Settings = {
   perMessageProfiles: false,
 
   cameraOnJoin: false,
+  // Tier default stays browser-native (known-good; best-perceived in testing so
+  // far). If a user opts into the ML tier, default to the highest-quality model.
   callNoiseSuppression: 'browser',
-  callDenoiseModel: 'rnnoise',
-  callDenoiseNativeNS: true,
+  callDenoiseModel: 'deepfilternet',
+  // "Series suppression" (stack the browser's native NS before the ML model) is
+  // off by default — best practice is a single NS stage; it's an opt-in test aid.
+  callDenoiseNativeNS: false,
   callDenoiseGate: false,
   callDenoiseGateThreshold: -45,
   pttMode: false,