source.coop: add more curated example products

Part of the source.coop integration roadmap. Depends on #197 (shared example datasets).

## Why

Adding curated source.coop products is the cheapest way to expand the example-datasets gallery. Each new product is a config-only addition — a new entry in \`source_coop_config.py\` (backend) and \`sourceCoopCatalog.ts\` (frontend), plus a thumbnail.

## What

Pick 2-4 more source.coop products that:
- Are already in one of the supported enumerator strategies (\`stac_sidecars\`, \`stac_sidecars\` recursive, or \`path_listing\`). Non-COG formats should wait for #XXX (PMTiles), #XXX (GeoParquet), #XXX (Zarr).
- Demonstrate a category not already represented by GHRSST (temporal raster), GEBCO (single-frame global), or Land & Carbon Lab (mosaic of COGs).
- Have clear public provenance / attribution.

Candidate categories worth covering:
- Land cover / classification raster
- Climate anomaly / reanalysis raster
- Regional high-resolution imagery (e.g., a recent disaster response product)
- Historical time-series (e.g., annual deforestation)

### Per product, add:
- Backend registry entry in \`ingestion/src/services/source_coop_config.py\`
- Frontend catalog entry in \`frontend/src/lib/sourceCoopCatalog.ts\`
- Thumbnail JPG in \`frontend/public/thumbnails/\`
- Description matching across the two sources

## Acceptance

- [ ] Gallery shows 5+ example cards
- [ ] Each new product registers at deploy time (via #197 startup task) and tiles correctly
- [ ] Thumbnails are real JPGs (not color-box placeholders)
- [ ] Categories represented are visibly distinct in the gallery (different thumbnails, different descriptions)

## Notes

- Spend 15-30 min browsing source.coop to pick products before starting the code change. The selection matters more than the implementation.
- If a candidate product is compelling but ships only as GeoParquet/PMTiles/Zarr, note it in a comment for when format support lands.