Use imports and run directive instead of script directive for Snakefiles / clarify how to debug Snakemake scripts

Maybe you could

• adapt the Snakemake rules to use run directives instead of script directives to allow for easier debugging in IDEs
  https://stackoverflow.com/questions/78677266/how-to-debug-scripts-for-pypsa-eur

• and/or include some hints in the documentation,

  • that snakemake does not support debuggin in IDEs if script or shell directive is used instead of run directive.
  • explain how the mocksnackemake workaround can be used for the purpose of debugging.
  • how to handle issues with missing files for that workaround. Is there an extra set of files that are always present for purpose of testing/debugging? Or does it use "regular" files, that need to be created running corresponding scripts/rules beforehand?

Related:

https://github.com/PyPSA/pypsa-eur/issues/1118

Start by reviewing the Snakefiles and the debugging discussion in issue #1118, then check how the script, shell, and run directives are currently used. Determine whether the contribution should document IDE debugging with mocksnakemake, including missing-file handling, or also change rules to use run directives. Done means the chosen scope is documented clearly and any agreed rule changes are covered by appropriate checks.