Live wall: pinned/docked cameras stop when their provider is switched off; admin-only empty-state CTA

- LiveView: localStorage pins carry image URLs, so they rendered (without
  credit) after an admin disabled the provider. Pins now show only while
  their provider is serving (server-26#198 licence gating).
- MapView: pinned/docked map players drop out once their provider leaves
  the serving list; credits are kept from the last answer so docked players
  keep attribution while the overlay is hidden.
- WallPanels: the "no camera provider enabled" link to /admin was a dead CTA
  for non-admins (bounced to /). Link shown to admins only, deep-linked to
  /admin#cameras; the admin page now honours a tab hash.

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

drb-frontend/components/LiveView.tsx

@@ -145,6 +145,10 @@ export function LiveView() {
   }, [pointsById, nodes]);
   const { data: cams, loaded: camsLoaded } = useCamerasInBbox(regionBox);
   const feeds = useMemo(() => new Map(cams.providers.map((p) => [p.id, p])), [cams.providers]);
+  // Pins live in this browser and carry their image URLs, so a pin must not
+  // outlive its provider: once an admin switches a provider off (licence
+  // gating, server-26#198) its pinned cameras stop rendering until it is back.
+  const servingPinned = useMemo(() => pinned.filter((c) => feeds.has(c.provider)), [pinned, feeds]);
   const nearById = useMemo(() => {
     const m = new Map<string, NearCamera[]>();
     pointsById.forEach((pts, id) => m.set(id, nearestCameras(pts, cams.cameras)));
@@ -158,19 +162,19 @@ export function LiveView() {
   const selectedPoints = selected ? pointsById.get(selected.incident_id) ?? [] : [];
   const near = selected ? nearById.get(selected.incident_id) ?? [] : [];
   const drillCam: Camera | null = link.cam
-    ? cams.cameras.find((c) => c.id === link.cam) ?? pinned.find((c) => c.id === link.cam) ?? null
+    ? cams.cameras.find((c) => c.id === link.cam) ?? servingPinned.find((c) => c.id === link.cam) ?? null
     : null;
 
   // Region wall: pinned first, then the nearest camera to each major/moderate incident.
   const wallCameras = useMemo(() => {
-    const out: { cam: Camera; km?: number }[] = pinned.map((cam) => ({ cam }));
+    const out: { cam: Camera; km?: number }[] = servingPinned.map((cam) => ({ cam }));
     for (const inc of sorted) {
       if (severityRank(inc.severity) < 2) continue;
       const first = nearById.get(inc.incident_id)?.[0];
       if (first && !out.some((o) => o.cam.id === first.cam.id)) out.push({ cam: first.cam, km: first.km });
     }
     return out.slice(0, 6);
-  }, [pinned, sorted, nearById]);
+  }, [servingPinned, sorted, nearById]);
 
   // ── Navigation ────────────────────────────────────────────────────────────
   const selectIncident = useCallback((id: string) => setLink({ inc: id, cam: null, tour: false }), [setLink]);