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/state/settings.ts

@@ -9,6 +9,11 @@ export type DateFormat =
   | 'YYYY-MM-DD'
   | '';
 export type MessageSpacing = '0' | '100' | '200' | '300' | '400' | '500';
+// Call mic noise suppression tier:
+//  - 'off'     : no suppression
+//  - 'browser' : WebRTC built-in suppression (Element Call noiseSuppression param)
+//  - 'ml'      : client-side RNNoise ML suppression (Lotus denoise shim)
+export type NoiseSuppressionMode = 'off' | 'browser' | 'ml';
 export type ChatBackground =
   | 'none'
   | 'blueprint'
@@ -109,7 +114,7 @@ export interface Settings {
   perMessageProfiles: boolean;
 
   cameraOnJoin: boolean;
-  callNoiseSuppression: boolean;
+  callNoiseSuppression: NoiseSuppressionMode;
   pttMode: boolean;
   pttKey: string;
 
@@ -199,7 +204,7 @@ const defaultSettings: Settings = {
   perMessageProfiles: false,
 
   cameraOnJoin: false,
-  callNoiseSuppression: true,
+  callNoiseSuppression: 'browser',
   pttMode: false,
   pttKey: 'Space',
 
@@ -235,6 +240,14 @@ export const getSettings = (): Settings => {
     return {
       ...defaultSettings,
       ...saved,
+      // Migrate legacy boolean callNoiseSuppression -> 3-way mode:
+      // true => browser-native, false => off. New string values pass through.
+      callNoiseSuppression:
+        typeof saved.callNoiseSuppression === 'boolean'
+          ? saved.callNoiseSuppression
+            ? 'browser'
+            : 'off'
+          : (saved.callNoiseSuppression ?? defaultSettings.callNoiseSuppression),
       composerToolbarButtons: {
         ...DEFAULT_COMPOSER_TOOLBAR,
         ...(saved.composerToolbarButtons ?? {}),