Weather map layers: NWS warning polygons, n0q radar with valid time/legend/loop, wind at incident (#237)

- Weather Warnings overlay (layer key `wx`, saved in the view hash): NWS alert
  polygons coloured by event (NWS hazard-map colours), outline dash by kind,
  popup with event/headline/expiry/office and National Weather Service credit.
  Polls GET /weather/alerts every 2 min while on and visible, refetches on pan.
  A status chip always says what the layer shows; feed errors use the 511
  FeedProblem wording; zone-only alerts are listed, never dropped.
- Radar: IEM nexrad-n0r -> n0q. Valid-time badge from IEM's n0q_0.json,
  STALE past 15 min or when the time can't be read; dBZ legend; optional 1 h
  loop (nexrad-n0q-900913-m05m..m55m), off by default. Still refreshed in
  place, never remounted.
- liveWall: sampleRadarDbz reads the n0q tile with IEM's published 255-colour
  ramp (verified against live tiles); pointInPolygon/alertsAt, wxStyle,
  wantsWind helpers.
- Wall incident panel: "inside <warning>" chips, wind arrow + speed/gust +
  station/obs time on fire/hazmat incidents; region Feeds gains an NWS row.

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

drb-frontend/lib/c2api.ts

@@ -1,6 +1,7 @@
 import { auth } from "@/lib/firebase";
 import type {
   AreaContext, CameraProviderAdmin, CamerasResponse, Ny511Response, OutageProviderAdmin, OutagesResponse, TalkgroupPending,
+  WeatherAlertsResponse, WindResponse,
 } from "@/lib/types";
 import type { DiscordAdminOverview, DiscordStream, RadioBot, RadioBotAddResult } from "@/lib/discord";
 
@@ -532,6 +533,16 @@ export const c2api = {
       body: JSON.stringify({ enabled, acknowledge_licence: acknowledgeLicence }),
     }),
 
+  // Weather context (server-26#237): active NWS alerts intersecting a bbox (bbox
+  // optional — omitted, the whole served area), and nearest-METAR wind. Both are
+  // cached server-side; an upstream failure comes back as `error`, not an HTTP error.
+  getWeatherAlerts: (bbox?: { south: number; west: number; north: number; east: number } | null) =>
+    request<WeatherAlertsResponse>(`/weather/alerts${bbox ? `?${new URLSearchParams({
+      south: String(bbox.south), west: String(bbox.west), north: String(bbox.north), east: String(bbox.east),
+    })}` : ""}`),
+  getWind: (lat: number, lon: number) =>
+    request<WindResponse>(`/weather/wind?${new URLSearchParams({ lat: String(lat), lon: String(lon) })}`),
+
   // 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) }),