Adopt the template for applications

Currently, the template is really focused on libraries, not on end-user software, such as ML or data analysis pipelines, web portals, scripts, etc. Researchers are more frequently starting a new end-user project than a library.

There are usually different expectations from end-user software than from a library: the environment should be reproducible, e.g., require some sort of a lock file; package data setup may be required; Dockerfile or entry points usually should be set up. I think the next "big thing" for PPT may be support for projects like that, while we can use in-house end-user projects to test it, e.g., hyrax (which, of course, is a library, but also a user-level script), hats-import scripts, "cone search v2.0", and individual team members' projects (I'd be happy to test it with uncle-val).

I propose to use uv for the lock file and tooling support, which makes it easy to manage virtual environments and gives a consistent way of running Python tools and commands via, e.g., uv run pytest and uv run python -m my-module.

Start by examining the current library-focused template and the end-user workflows named in the issue, including hyrax and hats-import. Assess how uv-managed lock files, reproducible environments, package data setup, Dockerfile support, and entry points should fit; done means an agreed template design for these application projects.