Docs: same-origin doc serving + usage URLs

Serve docs locally via app.py static mount (Dockerfile)

Serve docs locally via app.py static mount (app.py)

Add MosaicJSON (served same-origin)

Add STAC catalog (served same-origin)

Fix runtime: install libexpat1 for rasterio/GDAL

Deploy titiler (Docker): /mosaicjson + /stac for 1 m CHM

initial commit