captain: uv, logging, remote-Docker fixes, gha enhancements

[rpardini]

captain: uv, logging, remote-Docker fixes, gha enhancements

• 🍀 docker/mkosi: let /work be a regular directory, and mount specific files and dirs instead
  • this avoids remote-fs errors in mkosi when running against remote Docker daemon (eg: colima, Docker Desktop)
  • no, one can't simply mount tmpfs to /work/mkosi.tools -- mkosi wants to be able to delete it
  • ideally, mkosi.output (a misnomer?) would also be shared across invocations using a Volume (not yet though)
• 🐸 uv: pyproject.toml: add missing version field
  • so one can use uv run build.py without worrying about deps
• 🌳 docker/mkosi: add /cache/packages Docker Volume for download caching
  • this way we don't overwhelm Debian apt mirrors during development
• 🌱 python: use standard logging and Rich
  • drop all custom logging infra, standardize on logging
  • introduce Rich for logging & exception handling
  • replace custom progressbar with Rich's
• 🌿 python: switch to uv everywhere
  • switch from system-breaking pip to fully-contained uv
  • let uv install Python, don't use Debian's -- we get a single Python version for free
  • also: use Docker buildx explicitly; use plain output
  • build/docs: switch from plain Python+pip to uv; mention 3.13 instead of 3.10
  • consolidate usage of pyproject.toml; drop old requirements-dev.txt and requirements.txt
  • docker: run in interactive mode (tty) if isatty(), pass TERM/COLUMNS env
  • docker: prime uv's caches during Dockerfile build
• 🌵 gha: better all around GHA logging with colors and wide output
  • gha/docker: force Rich colored 160-wide console under GHA
    • pass down GITHUB_ACTIONS env so children can know
  • gha: reduce apt verbosity drastically with Dpkg::Use-Pty=0
• 🍃 gha: bump to cache restore/save v5 and download/upload-artifact v6
  • so gha stops complaining about Node.js 20
• 🌴 README.md: show uv install instructions and fix log.py and init.py