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/types.ts

@@ -319,6 +319,77 @@ export interface Ny511Response {
   credit?: CameraCredit;
 }
 
+// ── Weather context (server-26#237) — GET /weather/alerts, GET /weather/wind ──
+
+/** GeoJSON (Multi)Polygon, [lon, lat] order. */
+export type WeatherGeometry =
+  | { type: "Polygon"; coordinates: number[][][] }
+  | { type: "MultiPolygon"; coordinates: number[][][][] };
+
+/** One active NWS alert as c2-core normalises it (app/internal/weather.py normalize_alert). */
+export interface WeatherAlertBase {
+  id: string;
+  event: string;
+  severity: string | null;
+  urgency: string | null;
+  headline: string | null;
+  onset: string | null;
+  expires: string | null;
+  ends: string | null;
+  /** An NWS office ("NWS Upton NY"), never a person. */
+  sender_name: string | null;
+  area_desc: string | null;
+  zones: string[];
+}
+
+export interface WeatherAlert extends WeatherAlertBase {
+  geometry: WeatherGeometry;
+  /** "alert": NWS drew the polygon; "zones": assembled from the affected forecast/county zones. */
+  geometry_source: "alert" | "zones";
+  /** [south, west, north, east]. */
+  bbox: [number, number, number, number] | null;
+  /** >0: some zones could not be fetched, so the drawn area is smaller than the real one. */
+  zones_unresolved?: number;
+}
+
+export interface WeatherAlertsResponse {
+  alerts: WeatherAlert[];
+  /** Alerts with no resolvable shape — listed, never dropped, never bbox-filtered. */
+  zone_only: WeatherAlertBase[];
+  /** Epoch s of the server's last SUCCESSFUL NWS fetch; null = never. */
+  fetched_at: number | null;
+  /** Set when the latest refresh failed; `alerts` is then the last good data. */
+  error: string | null;
+  credit: string;
+}
+
+export interface WindObs {
+  station: string;
+  station_name: string;
+  lat: number;
+  lon: number;
+  obs_time: string | null;
+  /** Direction the wind blows FROM, degrees true; null when variable or calm. */
+  wind_dir_deg: number | null;
+  variable: boolean;
+  wind_kt: number;
+  gust_kt: number | null;
+  raw: string | null;
+  distance_km: number;
+  /** Report older than 2 h. */
+  stale: boolean;
+}
+
+export interface WindResponse {
+  available: boolean;
+  /** Why there is no wind, when `available` is false. */
+  reason: string | null;
+  wind: WindObs | null;
+  fetched_at: number | null;
+  error: string | null;
+  credit: string;
+}
+
 export interface VocabularyPendingTerm {
   term: string;
   source: "induction" | "correction";