feat(wind): add keyless NOAA GFS wind layer with animated particles

Add a Wind layer animating the global 10 m wind field from NOAA GFS.

The /api/wind proxy selects the latest available 0.25° cycle, reads its .idx
inventory, byte-range fetches only the UGRD/VGRD 10 m GRIB2 messages (~1 MB
each instead of the whole ~500 MB file), decodes them with ecCodes (WASM),
resamples to a compact grid (1° default), and serves a manifest plus a Float32
U/V payload cached per cycle for an hour (single-flight, last-good on failure).

The client renders nullschool-style particles in a canvas overlay: bilinear
field sampling with longitude wrap, per-frame advection, Cesium camera
projection, and globe-occlusion culling via EllipsoidalOccluder.

Validated end-to-end against the real 2026-09-14 06z cycle on Node 25
(180x91 grid at 2°, 131,040-byte payload, plausible mean |u|/|v|). The WASM
decoder requires Node >=24, which the repo already requires.

Registered as `wind` (token k) with attribution and docs. Verified: npm test
(3412 pass, 0 fail), npm run check:boundaries.

server/providers/wind/catalog.js

@@ -0,0 +1,16 @@
+export const GFS_BUCKET = 'noaa-gfs-bdp-pds';
+
+/** Build the public GFS object key. */
+export function gfsObjectKey({ date, hour, forecastHour = 0 }) {
+  const hh = String(hour).padStart(2, '0');
+  return `gfs.${date}/${hh}/atmos/gfs.t${hh}z.pgrb2.0p25.f${String(forecastHour).padStart(3, '0')}`;
+}
+
+/** Select the latest GFS cycle that should be available. */
+export function selectLatestGfsCycle(nowMs, { availabilityLagMs = 5 * 3600_000 } = {}) {
+  const d = new Date(nowMs - availabilityLagMs);
+  const date = new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate()));
+  const hour = Math.floor(d.getUTCHours() / 6) * 6;
+  date.setUTCHours(hour);
+  return { date: date.toISOString().slice(0, 10).replaceAll('-', ''), hour };
+}