call: consume self-built Element Call fork + activate Lotus features

Switch to @lotusguild/element-call-embedded@0.20.1-lotus.1 (our self-built
fork) and turn on the source-level features it adds:

- #1 denoise CUTOVER: in-source ML denoise (lotusDenoiseSource=1) replaces
  the build-time getUserMedia shim — removed the shim injection from
  vite.config.js (denoise/ assets still shipped; the processor loads them).
  Survives reconnects (fixes A7).
- #2 call-state: CallEmbed consumes io.lotus.call_state; useCallSpeakers /
  useRemoteAllMuted prefer it over scraping EC's DOM (DOM fallback kept;
  empty payloads ignored).
- #4 focus: CallControl.focusCameraParticipant sends io.lotus.focus_participant
  (works during screenshare), replacing the DOM tile-click hack.
- #5 theming: lotusTransparent=1 (native transparent background).
- #6 decorations: LotusDecorationPusher sends each member's decoration URL
  via io.lotus.decorations -> rendered on in-call tiles.

#3 soundboard / #7 quality ship dormant (EC-ready; no host UI sends them yet).

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

package.json

@@ -101,7 +101,7 @@
     "ua-parser-js": "2.0.10"
   },
   "devDependencies": {
-    "@element-hq/element-call-embedded": "0.20.1",
+    "@lotusguild/element-call-embedded": "0.20.1-lotus.1",
     "@rollup/plugin-inject": "5.0.5",
     "@rollup/plugin-wasm": "6.2.2",
     "@types/chroma-js": "3.1.2",