Add CI with pre-commit and smoke tests

[Yong2Sheng]

Summary

This PR adds lightweight GitHub Actions CI for the ResearchCodes repo and aligns local tooling so checks are reliable across machines.

What changed

• Add GitHub Actions workflow with two jobs:
  • pre-commit job runs repository hooks on all files in CI.
  • smoke job builds the conda environment from environment.yml and runs pytest -m smoke import checks.
• Tighten pre-commit hooks so auto-fix hooks only touch code and config files (prevents accidental edits to data files).
• Fix pytest configuration so smoke tests are discoverable in CI (tests directory is tracked, pytest marker registered).
• Clean up .gitignore to stop ignoring tests/ and remove unrelated project-specific ignore rules.

Why

• CI provides a clean-environment verification that environment.yml includes all required dependencies and that imports succeed.
• Running pre-commit in CI gives a consistent gate even if local hooks are skipped.
• Limiting auto-fix hooks avoids unintended modifications to important non-code data files.

How to test

• Local: pre-commit run --all-files --hook-stage pre-push
• Local: pytest -q -m smoke -x -ra
• CI: GitHub Actions runs both jobs on push and PR.

Notes

• Smoke test failure previously occurred because no tests were collected (pytest exit code 5) when tests/ was ignored; this PR ensures tests are tracked and discoverable.