Revamp

[kylebarron]

Change list

• Remove dependency on aiocache. User should be able to define caching themselves via the store input.
• Remove ctx. We shouldn't manage any "file context" inside of this class
• Update typing
• Expose header as public attribute in .header
• Remove io.py module with implementations for connecting to S3/GCS/Azure. Those connections should all happen via obstore.
• Rename Reader to PMTilesReader
• Add py.typed to declare as typed.
• Simplify pyproject.toml to use uv
• Update tests

Related upstream PRs

• Python: Improved type hints for pmtiles.tile protomaps/PMTiles#637
• Python: Deserialize from generic buffer protomaps/PMTiles#638

Questions

• I named the backend "store" to be consistent with obstore etc. We could call it client if preferred.
• Instead of having an async context manager, we can just have an async class constructor, like open. This matches how async-geotiff has await GeoTIFF.open(input). We don't have any resources to destroy so we don't need to have it be an async context manager.

Closes #5