feat: Add Sentinel-2 RGB to GeoZarr workflow with embedded STAC block

[wietzesuijker]

Adds Sentinel-2 (Vienna) to GeoZarr example with embedded STAC

• Queries Earth-Search for a low-cloud Sentinel-2 L2A scene over Vienna.
• Streams RGB COGs into xarray/rioxarray and writes a consolidated, 512 × 512-chunk GeoZarr dataset.
• Embeds a minimal STAC Item (proj:code, bbox, geometry, gsd, etc.) in root/.zattrs and calls zarr.consolidate_metadata.
• Reopens with xr.open_zarr(consolidated=True), prints the STAC block, and shows a 4 × 4 coarsened preview.

[emmanuelmathot]

@wietzesuijker, thank you for this notebook. I’m playing with it and trying to make it fully operational. Is it working for you? I’m currently stuck at ## Populate Zarr array with overview data, but I’ll keep going. I’m just curious about your progress.

[maxrjones]

This is great, thank you @wietzesuijker!

I know people are looking to build off this helpful example, so I will merge it after the zarr.consolidate_metadata comment is resolved and open a separate PR to apply light formatting (no substantive changes) and add it to the website.

[maxrjones]

@wietzesuijker I actually also think it would be best to pop the ds['spatial_ref'].attrs['spatial_ref'] attribute before writing to Zarr. Rioxarray adds the WKT to both the spatial_ref and crs_wkt attributes for compatibility with GDAL, but that redundancy should not be propagated to the stored metadata (spatial ref is not included in CF conventions but crs_wkt is included as a attribute for CRS information).

[wietzesuijker]

Thanks for the feedback. Ready for another review.