feat(calls): 3-tier mic noise suppression with on-device ML (P5-30)

Replace the boolean call noise-suppression setting with a 3-way control
(Off / Browser-native / ML beta) in Settings -> General -> Calls.

- Off: noiseSuppression=false to Element Call
- Browser-native: EC's built-in WebRTC suppressor (prior default)
- ML (beta): on-device RNNoise (@sapphi-red/web-noise-suppressor)

Element Call captures the mic inside its iframe and publishes to LiveKit,
so the host can't reach that track; LiveKit's Krisp filter is Cloud-only
(we self-host the SFU) and EC's own RNNoise PR #3892 is unmerged. The ML
tier instead injects a same-origin pre-init shim into the vendored EC
index.html (build/lotus-denoise.js, wired by the lotusDenoise vite plugin)
that patches getUserMedia and routes the captured mic through an RNNoise
AudioWorklet before LiveKit sees it -- the same post-capture pipeline as
#3892, with no EC fork/AGPL/rebase burden. Falls back to the raw mic if
setup fails; keeps echoCancellation/AGC on the raw capture.

- settings.ts: callNoiseSuppression -> 'off'|'browser'|'ml' + legacy
  boolean migration (true->browser, false->off)
- CallEmbed/useCallEmbed: tier maps to noiseSuppression param and appends
  lotusDenoise=ml (native suppressor off in ML mode)
- vite.config.js: copy RNNoise worklet/wasm + shim into the EC bundle and
  inject the shim <script> before EC's module entry
- docs: LOTUS_FEATURES.md, LOTUS_TODO.md (P5-30 done)

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

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

@@ -42,13 +42,11 @@ import {
   DateFormat,
   MessageLayout,
   MessageSpacing,
+  NoiseSuppressionMode,
   Settings,
   settingsAtom,
 } from '../../../state/settings';
-import {
-  SeasonalPreview,
-  SeasonTheme,
-} from '../../../components/seasonal/SeasonalEffect';
+import { SeasonalPreview, SeasonTheme } from '../../../components/seasonal/SeasonalEffect';
 import { SettingTile } from '../../../components/setting-tile';
 import { KeySymbol } from '../../../utils/key-symbol';
 import { isMacOS } from '../../../utils/user-agent';
@@ -1235,12 +1233,16 @@ function Calls() {
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile
           title="Noise Suppression"
-          description="Apply AI noise suppression to filter background noise during calls (powered by Element Call)."
+          description="Filter background noise from your mic during calls. Browser-native uses the built-in WebRTC suppressor; ML runs on-device RNNoise for stronger, Krisp-style removal (higher CPU)."
           after={
-            <Switch
-              variant="Primary"
+            <SettingsSelect<NoiseSuppressionMode>
               value={callNoiseSuppression}
               onChange={setCallNoiseSuppression}
+              options={[
+                { value: 'off', label: 'Off' },
+                { value: 'browser', label: 'Browser-native' },
+                { value: 'ml', label: 'ML (beta)' },
+              ]}
             />
           }
         />
@@ -1346,22 +1348,25 @@ function Calls() {
   );
 }
 
-const SEASONAL_OPTIONS: { value: Settings['seasonalThemeOverride']; label: string; emoji: string }[] =
-  [
-    { value: 'auto', label: 'Auto', emoji: '🗓' },
-    { value: 'off', label: 'Off', emoji: '×' },
-    { value: 'newyear', label: 'New Year', emoji: '🎆' },
-    { value: 'lunar', label: 'Lunar New Year', emoji: '🏮' },
-    { value: 'valentines', label: "Valentine's", emoji: '💖' },
-    { value: 'stpatricks', label: "St. Patrick's", emoji: '🍀' },
-    { value: 'aprilfools', label: 'April Fools', emoji: '?' },
-    { value: 'earthday', label: 'Earth Day', emoji: '🌱' },
-    { value: 'autumn', label: 'Autumn', emoji: '🍂' },
-    { value: 'halloween', label: 'Halloween', emoji: '🎃' },
-    { value: 'christmas', label: 'Christmas', emoji: '❄️' },
-    { value: 'arcade', label: 'Arcade Day', emoji: '👾' },
-    { value: 'deepspace', label: 'Deep Space', emoji: '🚀' },
-  ];
+const SEASONAL_OPTIONS: {
+  value: Settings['seasonalThemeOverride'];
+  label: string;
+  emoji: string;
+}[] = [
+  { value: 'auto', label: 'Auto', emoji: '🗓' },
+  { value: 'off', label: 'Off', emoji: '×' },
+  { value: 'newyear', label: 'New Year', emoji: '🎆' },
+  { value: 'lunar', label: 'Lunar New Year', emoji: '🏮' },
+  { value: 'valentines', label: "Valentine's", emoji: '💖' },
+  { value: 'stpatricks', label: "St. Patrick's", emoji: '🍀' },
+  { value: 'aprilfools', label: 'April Fools', emoji: '?' },
+  { value: 'earthday', label: 'Earth Day', emoji: '🌱' },
+  { value: 'autumn', label: 'Autumn', emoji: '🍂' },
+  { value: 'halloween', label: 'Halloween', emoji: '🎃' },
+  { value: 'christmas', label: 'Christmas', emoji: '❄️' },
+  { value: 'arcade', label: 'Arcade Day', emoji: '👾' },
+  { value: 'deepspace', label: 'Deep Space', emoji: '🚀' },
+];
 
 function SeasonalBgGrid({
   value,