OSGeo/PROJ ? reverse-engineered prompt

Build me a coordinate transformation library that can take positions from one coordinate system and convert them to another, including map projections and geodetic calculations.

I want it to come with command line tools for things like projecting coordinates, converting between systems, doing geodesic distance and path calculations, and looking up available coordinate operations. Please include support for projection and transformation data files, and make it work both with local data and with downloading missing resources when needed. If anything needs current reference details, look up the latest docs online before wiring it up.

Make it feel like a real production geospatial toolkit, with good documentation, example usage, install instructions, and a test suite that covers the main transformations. Keep the code organized so it can be built as a reusable library and used from the command line.