be sync, migration, featuring pre-live web cast

docs/DRs/20260620_live_cast_control_plane.md

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+# Live Cast Control Plane (P0-P2 kickoff)
+
+## Scope implemented
+
+- New BE API `POST/GET .../api/live_cast.php`:
+  - `create_intent`, `heartbeat` (60s KA), `join_event`
+  - `GET action=active|analytics|session|list`
+  - Public (no login): `session`, `join_event`, education `create_intent`/`heartbeat`
+- New BE repository `LiveCastRepository` with auto-schema:
+  - `live_cast_sessions`, `live_cast_join_events`
+- Expiry rule: sessions without heartbeat for 60s become `expired`.
+- Short links + QR per session (join + direct) via internal short-links service.
+- Analytics payload includes `live_cast` section; shell label **Analytics**.
+- Web pages:
+  - `/live/join` — viewer entry, join_event tracking, player placeholder
+  - `/live/education` — 5-minute browser screen-share demo
+  - `?view=live_sessions` — session tree (read-only, auto-refresh)
+- Cookie consent banner (`cookie_consent.js`) gates GA4 until user accepts.
+- Mobile:
+  - `LiveCastControlPlane` — start/heartbeat/stop from sender/receiver services
+  - `LiveCastPeerTracker` — polls `active` sessions; green border on discovery list
+
+## Non-goals (remaining)
+
+- WebRTC/SFU media plane and real HTML5 playback.
+- Push notification delivery (Web Push / FCM).
+- Gravatar / refined avatar chrome on web lists.
+- Short-link click counter migration in url-shortener submodule.
+
+## Data model notes
+
+`live_cast_sessions` stores owner/device/platform, state transitions, short URLs, codec/BW hints.  
+`live_cast_join_events` stores open/join/leave events with platform/channel/direct flags and basic anon dimensions.
+
+## Follow-up phases
+
+1. Integrate SFU/web viewer when media-plane branch is ready.
+2. Browser/mobile notification fan-out on cast start.
+3. Gravatar + green-border on web peer lists.
+4. Shortener click stats joined into live session analytics.