android(call): Increment 2a — native LiveKit call audio, background service, speaker/BT routing

Replaces WebView call media on Android with a native LiveKit connection (iOS
parity), so call audio survives backgrounding and the output can be switched
to Speaker/Bluetooth/Earpiece — the #3 (missing speaker control) and #4
(background audio) items.

Gated behind a new, default-off server flag ANDROID_NATIVE_MEDIA (independent
of ANDROID_CALLS, which only governs the native ring). Flag off = today's
WebView media, video included; flag on = native audio (video is Increment 2b,
so enable it for VOICE testing first). No behavior change until flipped.

Native (mobile/plugins/native-call/android):
- build.gradle: add kotlin-android + io.livekit:livekit-android 2.29.2 (+ twilio
  audioswitch, coroutines) + JitPack repo; minSdk 24 (LiveKit floor).
- CallMedia.kt: LiveKit Room wrapper — connect/mic/disconnect + AudioSwitchHandler
  routing (auto + selectDevice) and route-change events.
- CallForegroundService.java: microphone-type foreground service for background
  audio (no-ops without RECORD_AUDIO so it never crashes the call).
- NativeCallPlugin.java: real bodies for reportOutgoingCall/reconnectRoom/setMuted
  /endCall + new setAudioRoute/getAudioRoute; fires callConnected/callError/audioRoute.
- AndroidManifest: FG service + FOREGROUND_SERVICE(_MICROPHONE)/RECORD_AUDIO/
  MODIFY_AUDIO_SETTINGS/BLUETOOTH_CONNECT.
- android-patch.js: bump the generated app minSdk to 24.

Server:
- config.js/routes.js: ANDROID_NATIVE_MEDIA → /api/meetings/config.androidNativeMedia.

Web (home.html):
- Android flips to the native-media path when androidNativeMedia is set; the
  existing outgoing/answer/mic/end code then drives the plugin unchanged.
- Speaker button wired for Android native: cycles speaker/earpiece/bluetooth via
  NC.setAudioRoute and reflects the real output from the audioRoute event.

Video stays no-op on the native path (Increment 2b).

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

server/routes.js

@@ -116,7 +116,7 @@ const API_KEY_SCOPES = ['report:read', 'audit:read'];
 const { onlineAgents, meetingRooms, groupCalls, dmCalls } = require('./presence');
 const CALLS = require('./calls');
 require('./reminders'); // start the 10-minute meeting-reminder loop
-const { REC_DIR, TRANS_DIR, UPLOADS_DIR, SESSION_TTL, REFRESH_TTL, LIVEKIT_URL, LIVEKIT_API_KEY, LIVEKIT_API_SECRET, LIVEKIT_ENABLED, PUBLIC_BASE_URL, GIPHY_API_KEY, CALLKIT_ENABLED, ANDROID_CALLS } = require('./config');
+const { REC_DIR, TRANS_DIR, UPLOADS_DIR, SESSION_TTL, REFRESH_TTL, LIVEKIT_URL, LIVEKIT_API_KEY, LIVEKIT_API_SECRET, LIVEKIT_ENABLED, PUBLIC_BASE_URL, GIPHY_API_KEY, CALLKIT_ENABLED, ANDROID_CALLS, ANDROID_NATIVE_MEDIA } = require('./config');
 const https = require('https');
 // Small GET-JSON helper for the GIPHY proxy (keeps the key server-side).
 function fetchJSON(url) {
@@ -993,7 +993,7 @@ route('POST', '/api/calls/invite', async (req, res) => {
 // Does this deployment use the LiveKit SFU for meeting media? The client asks on load; if sfu is
 // false it uses the built-in P2P mesh. url is the browser-facing signaling endpoint (wss://…).
 route('GET', '/api/meetings/config', (req, res) => {
-  json(res, 200, { sfu: LIVEKIT_ENABLED, url: LIVEKIT_ENABLED ? LIVEKIT_URL : '', callkit: CALLKIT_ENABLED, androidCall: ANDROID_CALLS, fcm: PUSH.fcmReady() });
+  json(res, 200, { sfu: LIVEKIT_ENABLED, url: LIVEKIT_ENABLED ? LIVEKIT_URL : '', callkit: CALLKIT_ENABLED, androidCall: ANDROID_CALLS, androidNativeMedia: ANDROID_NATIVE_MEDIA, fcm: PUSH.fcmReady() });
 });
 
 // #5 GIF search — server-side GIPHY proxy so the API key never reaches the browser. Empty q → trending.