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/routers/cameras.py

@@ -0,0 +1,51 @@
+"""Public-camera endpoints for the live ops wall.
+
+``GET /cameras`` -- any signed-in user (auth applied at include time in main.py):
+cameras inside a bbox from every provider an admin has enabled, each with the
+provider's required attribution, disclaimer and catalog freshness.
+
+``/admin/camera-providers`` -- platform admin only: list every catalogued
+provider with its licence status and health, and toggle it. Gated licences
+need ``acknowledge_licence: true``; that acknowledgement is stored with who and
+when and written to audit_log (see app/internal/cameras/registry.py).
+"""
+from fastapi import APIRouter, Depends, HTTPException, Query
+from fastapi.responses import JSONResponse
+from pydantic import BaseModel
+
+from app.internal.auth import describe_actor, require_admin_token
+from app.internal.cameras import registry
+
+router = APIRouter(prefix="/cameras", tags=["cameras"])
+admin_router = APIRouter(prefix="/admin/camera-providers", tags=["admin"])
+
+
+@router.get("")
+async def get_cameras(
+    south: float = Query(..., ge=-90, le=90),
+    west: float = Query(..., ge=-180, le=180),
+    north: float = Query(..., ge=-90, le=90),
+    east: float = Query(..., ge=-180, le=180),
+):
+    if south > north or west > east:
+        raise HTTPException(400, "bbox must satisfy south<=north and west<=east")
+    return await registry.cameras_in_bbox((south, west, north, east))
+
+
+class ProviderToggle(BaseModel):
+    enabled: bool
+    acknowledge_licence: bool = False
+
+
+@admin_router.get("")
+async def list_camera_providers(_=Depends(require_admin_token)):
+    return {"providers": await registry.list_providers()}
+
+
+@admin_router.put("/{provider_id}")
+async def set_camera_provider(provider_id: str, body: ProviderToggle, principal: dict = Depends(require_admin_token)):
+    try:
+        return await registry.set_enabled(provider_id, body.enabled, describe_actor(principal),
+                                          acknowledge_licence=body.acknowledge_licence)
+    except registry.ProviderError as e:
+        return JSONResponse(status_code=e.code, content={"detail": e.message, **e.extra})