feat: add continuous integration and deployment documentation, including CI stages, local testing, and Kubernetes deployment guidelines

CONTRIBUTING.md

@@ -40,4 +40,42 @@ This ensures the API headers, download content, and modal routes remain function
 
 Once you are satisfied with your changes, submit a pull request to the main repository.
 
+## Continuous Integration
+
+Calminer uses Gitea Actions for automated testing, linting, and deployment. The CI pipeline is defined in `.gitea/workflows/cicache.yml` and runs on pushes and pull requests to the `main` and `develop` branches.
+
+### Pipeline Stages
+
+1. **Lint**: Checks code style with Ruff and Black.
+2. **Test**: Runs pytest with coverage enforcement (80% threshold), using a PostgreSQL service. Uploads coverage.xml and pytest-report.xml artifacts.
+3. **Build**: Builds Docker image and pushes to registry only on `main` branch pushes (not PRs) if registry secrets are configured.
+
+### Workflow Behavior
+
+- Triggers on push/PR to `main` or `develop`.
+- Linting must pass before tests run.
+- Tests must pass before build runs.
+- Coverage below 80% fails the test stage.
+- Artifacts are available for PR inspection.
+- Docker push occurs only for main branch commits with valid registry credentials.
+
+### Local Testing
+
+To replicate CI locally:
+
+```bash
+# Install test deps
+pip install -r requirements-test.txt
+
+# Run linting
+ruff check .
+black --check .
+
+# Run tests with coverage
+pytest --cov=. --cov-report=term-missing --cov-fail-under=80
+
+# Build image
+docker build -t calminer .
+```
+
 Thank you for your interest in contributing to Calminer!