[SYSTEMDS-3427] CodeCoverage Python

[aperov9]

This pull request introduces test coverage reporting for the Python-based code base & uploads the merged coverage to codecov.

CI/CD and Coverage Reporting Enhancements

• Updated the Python workflow to install the coverage package, run tests with coverage enabled for all test modes (including federated and scuro), and collect per-mode coverage data files. Added a new job to merge these coverage files, generate a combined report, and upload it to Codecov and as workflow artifacts.
• Modified the Java test workflow to tag Codecov uploads with a java flag for clearer separation of coverage data.
• Please make sure to enable the flag feature in codecov.

Documentation and Badge Updates

• Updated the README.md to display separate Codecov badges for Java and Python coverage.

Python Coverage Configuration

• Added a .coveragerc configuration file in src/main/python to omit irrelevant files (such as those generated by OpenCV and PyTorch) from coverage analysis.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.67%. Comparing base (0260387) to head (41e2f3c).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2359      +/-   ##
============================================
+ Coverage     71.65%   71.67%   +0.01%     
- Complexity    47383    47396      +13     
============================================
  Files          1536     1536              
  Lines        181966   181966              
  Branches      35757    35757              
============================================
+ Hits         130393   130416      +23     
+ Misses        41658    41639      -19     
+ Partials       9915     9911       -4     

Flag	Coverage Δ
java	71.67% <ø> (?)

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🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[christinadionysio]

@aperov9 could you please merge main into this commit so I can trigger a rerun of the codecov action?

[aperov9]

Done @christinadionysio

[aperov9]

Hmm, seems like something doesn't work anymore for the python test, will check that. However, the java tests should run, I did not touch anything there. Can you confirm that the tests are just flaky or that is broken on main? @christinadionysio

[christinadionysio]

Hmm, seems like something doesn't work anymore for the python test, will check that. However, the java tests should run, I did not touch anything there. Can you confirm that the tests are just flaky or that is broken on main? @christinadionysio

@aperov9 the java tests are running now, would be great if you could look into the failing python tests.