Write a CI/CD Test Pipeline

Write a GitHub Actions workflow file for CI/CD testing on pull requests.

Project details:
- Language: [TYPESCRIPT / PYTHON / GO / etc.]
- Test runner: [JEST / PYTEST / GO TEST / etc.]
- Linter: [ESLINT / RUFF / GOLINT / etc.]
- Package manager: [NPM / YARN / PIP / etc.]
- Node/runtime version: [VERSION]

Workflow requirements:
- Trigger: on pull_request and push to main
- Jobs to run: install, lint, test, type check (if applicable)
- Cache dependencies for faster runs
- Report test coverage if available
- Fail fast on errors
- Add a badge-compatible status check

Include comments explaining each step. Output the complete .github/workflows/ci.yml file.