feat: Initial, most basic GeoZarr example

[kylebarron]

Data is served locally right now, generated via developmentseed/geozarr-examples#36

Screen.Recording.2026-04-07.at.4.16.18.PM.mov

Change list

• New ZarrLayer that roughly parallels the COGLayer, using zarrita.js and looking for GeoZarr metadata
  • For now it hard-codes the expectation that the input is an RGB GeoZarr, but that will be refactored and expanded soon.
• New zarr-sentinel2-tci example that renders a Sentinel2 image converted to GeoZarr with scratch work to assign spatial:transform when creating geozarr metadata geozarr-examples#36
• renderDebugTileOutline was shared exactly between COGLayer and ZarrLayer, so it was moved into deck.gl-raster to be shared

I think in the future we'll have more things that move into deck.gl-raster as utilities that can be shared across both the COGLayer and the ZarrLayer.