[Enhancement] Add CI/CD pipeline and unit test framework

[GaneshPatil7517]

Currently the only GitHub Actions workflow is draft-pdf.yml (for JOSS paper generation). There are:

• No unit tests anywhere in the repository
• No automated testing on push/PR
• No linting checks
• No build verification for C++, Java, or Verilog
• No Dockerfile build checks

This means any code change (including new language implementations like Julia) has zero automated validation for regressions.

Proposed additions:

1. test_concore.py Unit tests for read(), write(), unchanged(), initval(), tryparam(), default_maxtime()
2. GitHub Actions workflow:
   Python: pip install + pytest
   Lint: ruff or flake8
   Sample study execution
   Dockerfile build validation
3. Test coverage reporting via Codecov

[GaneshPatil7517]

hey @pradeeban I'd be happy to contribute a PR implementing this if you agree with the approach.