merge: integrate ECMWF IFS PR #464 with bounded model switching

DATA_SOURCES.md

@@ -142,6 +142,10 @@ transaction quota. Requires a free `FIRMS_MAP_KEY`
 (https://firms.modaps.eosdis.nasa.gov/api/map_key/); the layer is empty without it.
 The former bundled 2026-05-25 snapshot was removed 2026-07-16.
 
+### ECMWF IFS wind
+
+Wind also offers ECMWF IFS 10 m forecasts from the keyless [ECMWF Open Data](https://www.ecmwf.int/en/forecasts/datasets/open-data) service. The proxy reads its JSON Lines inventory and fetches only 10u/10v GRIB messages, resampling the forecast to the display grid. Data is licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). Attribution: “Contains modified Copernicus/ECMWF IFS forecast data.” Both model issue time and the selected forecast valid time appear in the layer row. These are model forecasts, not observations.
+
 ### NOAA GFS wind
 
 The optional **Wind** layer animates the global 10 m wind field from NOAA's
@@ -197,3 +201,4 @@ Douglas-Peucker simplification, 6-decimal rounding).
 ## In-app attribution
 
 The required Google Maps / Cesium credit renders on the on-globe credit line (`#cesium-credits`, bottom-left) and must stay visible — including in clean-view and recording modes (the whole line, logo + "Google Maps" + the "Data attribution" link, stays on screen; only the GEV panels/HUD fade). The layer-specific credits (adsb.lol, TeleGeography, OSM datacenters/dams/roads, NASA FIRMS, CelesTrak, USGS, City of Austin, Fintraffic, GBFS, Radio Browser, OpenSky, AISStream) are registered into the expandable **"Data attribution"** popover on that credit line via `viewer.creditDisplay.addStaticCredit(new Cesium.Credit(html, /* showOnScreen */ false))` — see `src/data/dataCredits.js`. When you add a new data source, add its license and attribution to this file **and** append an entry to `DATA_CREDITS` in `src/data/dataCredits.js` so it surfaces in the app.
+