feat: LAN Wi-Fi casting to Chromecast via local HTTP relay

Re-serve decrypted fMP4 video over HTTP on the LAN so a Chromecast can
play the stream. The relay runs in the Electron main process — same trust
boundary as downloads and MSE playback.

- cast-relay.js: HTTP server with BoxAccumulator (reassembles WebRTC
  chunks into moof+mdat pairs), ring buffer, backpressure, finish() for
  clean end-of-stream, fixed port range 19550-19553
- cast-chromecast.js: mDNS discovery (bonjour-service) + CASTV2 protocol
  (castv2-client), connect/reload/disconnect lifecycle
- Seek-aware: relay restarts on every seek, Chromecast reloads new URL;
  generation counter prevents stale async errors from killing active
  restarts; landingPlayheadRef suppresses programmatic seeking events
- Device picker in video top bar with scan, device selection, copy-URL
  fallback, and cast status indicator
- IPC bridge (main/preload/platform) for start/push/stop/finish/status/
  discover/chromecastConnect/chromecastReload/chromecastDisconnect
- Phase 3 design doc for DLNA/Smart TV in docs/cast-smart-tv.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
index aa3899d..1a68827 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
@@ -150,6 +150,14 @@ export default {
   'video.err_transport': 'トランスポートが接続されていません',
   'video.err_mse': 'ストリーミング再生に対応していないコーデックです：{codec}',
 
+  // LAN cast
+  'cast.start': 'デバイスにキャスト',
+  'cast.stop': 'キャストを停止',
+  'cast.copy_url': 'ストリームURLをコピー',
+  'cast.copied': 'URLをコピーしました',
+  'cast.scanning': 'デバイスを検索中…',
+  'cast.no_devices': 'デバイスが見つかりません',
+
   // Settings
   'settings.title': '設定',
   'settings.coming_soon': '近日公開。',