Add TiTiler endpoints for zarr datasets

[turban]

This PR adds new TiTiler "/zarr" endpoints allowing tiles to be generated from a zarr folder (or an url).

It also includes a PROJ path check in startup.py to make sure the correct PROJ dependency is used with uv.

Example tile urls:

http://127.0.0.1:8000/zarr/tiles/WebMercatorQuad/12/1913/1949?url=data/downloads/worldpop_population_yearly.zarr&variable=pop_total&sel=time=2026-01-01&colormap_name=ylorbr

Returns:

http://127.0.0.1:8000/zarr/tiles/WebMercatorQuad/9/239/244?url=data/downloads/worldpop_population_yearly.zarr&variable=pop_total&sel=time=2026-01-01&colormap=[[[0,5],[254,229,217]],[[5,10],[252,187,161]],[[10,15],[252,146,114]],[[15,20],[251,106,74]],[[20,25],[222,45,38]],[[25,10000],[165,15,21]]]

(GEE version to the right)

[Copilot]

Pull request overview

This PR adds TiTiler xarray-backed tile endpoints to eo-api, wiring a new router into the FastAPI app and introducing early-boot PROJ data configuration to avoid CRS/proj.db issues when importing raster tooling.

Changes:

• Add titiler-xarray (and its transitive deps) to the project dependencies/lockfile.
• Introduce a tiles package that exposes a TiTiler tiles_router based on xarray/zarr.
• Configure PROJ data env vars during startup to prefer the active Python environment’s PROJ data.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
pyproject.toml	Adds titiler-xarray as an application dependency.
uv.lock	Locks titiler-xarray and new transitive deps (e.g., obstore).
src/eo_api/tiles/titiler.py	Defines a TiTiler xarray TilerFactory router for zarr/xarray tiling.
src/eo_api/tiles/__init__.py	Exports tiles_router for easy import/registration.
src/eo_api/startup.py	Adds PROJ env var configuration during early-boot side effects.
src/eo_api/main.py	Mounts the new tiles router under /zarr.

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