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/utils/lotusDenoiseUtils.test.ts

@@ -1,18 +1,14 @@
 import { test, beforeEach, afterEach } from 'node:test';
 import assert from 'node:assert/strict';
 
-import {
-  DENOISE_MODELS,
-  ML_DENOISE_REQUIREMENTS,
-  isMLDenoiseSupported,
-} from './lotusDenoiseUtils';
+import { DENOISE_MODELS, ML_DENOISE_REQUIREMENTS, isMLDenoiseSupported } from './lotusDenoiseUtils';
 
 // ── Model catalog (data integrity) ──────────────────────────────────────────
 
-test('DENOISE_MODELS lists the four expected models in order', () => {
+test('DENOISE_MODELS lists the four models ordered best-quality (highest CPU) first', () => {
   assert.deepEqual(
     DENOISE_MODELS.map((m) => m.id),
-    ['rnnoise', 'speex', 'dtln', 'deepfilternet'],
+    ['deepfilternet', 'dtln', 'rnnoise', 'speex'],
   );
 });