511NY DOT cameras + traffic events map layers (#183)

GET /traffic/511 serves a bbox slice of the statewide 511NY camera and event
feeds from an in-memory cache (cameras 1h, events 2m TTL, fetched lazily) --
public data, so no Firestore writes. A failed refresh keeps the last good data
and reports the error; a schema change (nothing parses) is an error, not an
empty layer. Frontend: opt-in "DOT Cameras" and "Traffic Events" overlays that
fetch only while shown, with an on-map notice when the feed is down or stale.
NY511_API_KEY is optional in config (the API answers without one today; the
terms require a registered key).

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

drb-frontend/lib/c2api.ts

@@ -1,5 +1,5 @@
 import { auth } from "@/lib/firebase";
-import type { AreaContext, TalkgroupPending } from "@/lib/types";
+import type { AreaContext, Ny511Response, TalkgroupPending } from "@/lib/types";
 
 const BASE = process.env.NEXT_PUBLIC_C2_URL ?? "http://localhost:8000";
 
@@ -370,6 +370,12 @@ export const c2api = {
   revokeEnrollmentToken: (tokenId: string) =>
     request(`/org/enrollment-tokens/${tokenId}`, { method: "DELETE" }),
 
+  // 511NY cameras/events inside a map bbox (server-26#183)
+  get511: (bbox: { south: number; west: number; north: number; east: number }, layers: string) =>
+    request<Ny511Response>(`/traffic/511?${new URLSearchParams({
+      south: String(bbox.south), west: String(bbox.west), north: String(bbox.north), east: String(bbox.east), layers,
+    })}`),
+
   // Public waitlist — no auth, see routers/waitlist.py
   joinWaitlist: (body: { email: string; org_name?: string; note?: string }) =>
     request<{ ok: boolean }>("/waitlist", { method: "POST", body: JSON.stringify(body) }),