Live ops wall + pluggable camera providers with licence gating (server-26#198)

Backend (c2-core):
- app/internal/cameras/: provider interface, licence model, per-provider
  catalog cache; one adapter per source in design-canvas/camera-sources.md.
  Implemented: 511NY (legacy shape + tolerant XML inventory parser, 511x
  endpoints UNVERIFIED), Caltrans, DelDOT, Ontario 511, DriveBC, Calgary,
  TfL, NSW, Fintraffic. Stubs: NYC DOT, Westchester DPW, TRANSCOM, CTroads,
  511NJ, Austin, TxDOT, MD CHART, WSDOT, Tallinn, Tarktee, Warendorf,
  TrafficLand, Windy, EarthCam.
- Every provider defaults OFF (config/camera_providers). Gated licences
  (agreement required / unverified / non-commercial / paid) need an explicit
  acknowledgement stored with who/when and written to audit_log; the audit
  write is a precondition. Stubs and prohibited sources cannot be enabled.
  Ack is bound to the licence status it was given for.
- GET /cameras (signed-in), GET/PUT /admin/camera-providers (admin only).
- /traffic/511 follows the ny511 provider switch and returns the DAA credit
  + NYSDOT as-is disclaimer; 511NY event descriptions no longer truncated
  ("may not alter the substance of a report").

Frontend:
- LiveView becomes the ops wall: Region > Incident > Camera drill-down,
  worst-first rail (MapView), KPIs, transcript ticker, scrubber incident
  bands, auto-tour, deep links (#inc=&cam=&tour), Esc steps up.
- Incident panel: nearest cameras (path-weighted), fused situational context
  (ADS-B, AIS, 511NY events, NEXRAD tile sample), units, call spine.
- MapView keeps every layer; adds Camera Viewsheds (approx.) overlay and a
  nearest-camera layer for the selected incident.
- CameraFeed hygiene: hidden-tab/off-screen gating, 2 concurrent HLS cap,
  last good frame + stale badge, frozen-frame signature, HLS stall watchdog,
  provider attribution rendered on the imagery.
- Camera/event popups show source credit, update time and the disclaimer.
- Admin > Camera providers tab with licence status, health, gated confirm.
- Camera detection is not built (blocked on #199/#200); seam only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-c2-core/app/main.py

@@ -17,7 +17,7 @@ from app.internal.auth import (
     require_node_service_or_firebase_token,
 )
 from app.routers import nodes, systems, calls, upload, tokens, incidents, alerts, admin, trips, places, links, users
-from app.routers import enrollment, media, org, waitlist, telemetry, replay, traffic
+from app.routers import enrollment, media, org, waitlist, telemetry, replay, traffic, cameras
 from app.internal import dynsec
 from app.internal import firestore as fstore
 
@@ -128,6 +128,8 @@ app.include_router(alerts.router,    dependencies=[Depends(require_service_or_fi
 app.include_router(trips.router,     dependencies=[Depends(require_service_or_firebase_token)])
 app.include_router(places.router,    dependencies=[Depends(require_service_or_firebase_token)])
 app.include_router(traffic.router,   dependencies=[Depends(require_service_or_firebase_token)])
+app.include_router(cameras.router,   dependencies=[Depends(require_service_or_firebase_token)])
+app.include_router(cameras.admin_router)  # auth: admin only, per endpoint (needs the principal for audit)
 app.include_router(upload.router)    # auth is per-node, handled inline
 app.include_router(admin.router)     # auth is per-endpoint (read: firebase, write: admin)
 app.include_router(replay.router)    # auth: admin only (every route spends or reads a replay run)