Add Python Actions tutorial based on elastic-tube-1d

[kishansinghifs1]

Add Python callback interface tutorial and related scripts for elastic-tube-1d #617

1. Added a complete Python callback interface workflow (precice-config-callback.xml, solver wrappers, and run scripts) alongside the baseline elastic tube case without modifying existing functionality.
2. Created pressureRampAction.py with a performAction(...) function that applies a time-dependent pressure ramp (t < 0.2) via the preCICE Python callback interface.

Checklist:

• I added a summary of any user-facing changes (compared to the last release) in the changelog-entries/<PRnumber>.md.
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.

[precice-bot]

This pull request has been mentioned on preCICE Forum on Discourse. There might be relevant details there:

https://precice.discourse.group/t/gsoc-2026-kishan-singh-system-tests-improvements/2775/1

[fsimonis]

The Python actions is a feature that is on the slippery slope towards undefined behavior.
There definitely is an issue when mixing time-window sizes.

We at least need to verify the results of this implementation.

A more strategic question is whether we even want to promote this feature.

@uekerman @MakisH

[uekerman]

Verifying the results for his PR should be easy enough. I am rather sure that the Python actions still work here.

That the possibilities of the actions are vast is clear. I agree that we should eventually restrict these or even remove the feature completely. But here is probably not the best place for this discussion.

Despite all this, the solution in this PR seems too complicated IMO.
A cleaner solution could be to even simply overwrite the elastic tube to always do the ramp?