docs: add Cursor PR workflow rule and exclude mdc from ruff

[ideepu]

Summary

• Add a Cursor rule (.cursor/rules/create-pr.mdc) documenting the PR workflow for this repo: branch naming, commit conventions, pre-PR checks, and gh pr create steps.
• Exclude *.mdc files from ruff so Cursor rule files are not linted as Python.

Test plan

• make lint
• make test

[ideepu]

Coverage report

  

This PR does not include changes to coverable code or code with missing coverage.

Click to see whole project coverage

File	Statements	Missing	Branches	Missing	Coverage	Missing stmts	Missing branches
codecov
config.py						99
github.py							207->219
github_client.py						128, 130	127->130
main.py						119-120	118->119
codecov/coverage
base.py						75-77, 102-104	54->56
jest.py						65-69, 73-74, 77-88, 94-106, 112-126, 145-159, 175-179, 194-212, 217	67->102, 150->158, 199->212
Project Total

See the full coverage report of the project here.

_{This report was generated by codecov}