Define guidelines for base image structure/style

[slint]

We currently don't have any guidelines on how we want the base Invenio Docker images to be built. Some examples of things that need to be defined:

• Python distribution
  • Should we use the Python distribution that comes with the base image? E.g. python:3.13 or python:3.13-alpine?
  • Should we install a specific "standalone" Python version using...
    • ...the distro's package manager (yum, apt, ...)?
    • ...uv python install ...?
• Node.js distribution
  • Same as above
• How should we install other dev dependencies like libxml, libpng, etc.?
• Should we already try to optimize for image size using multi-stage builds, or is this something that "downstream" consumers ensure for their application images?