chore: add GitHub Copilot instructions

.github/copilot-instructions.md

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+# GitHub Copilot Instructions for Loculus
+
+## About Loculus
+
+Loculus is a software package to power microbial genomic databases. It supports upload and storage of consensus sequences and metadata, flexible data preprocessing, powerful searches, and is highly configurable for both single- and multi-segmented genomes.
+
+## Project Structure
+
+The repository is organized into several key components:
+
+- **`backend/`** - Kotlin backend service (Spring Boot)
+- **`website/`** - Frontend web application (Astro, React, TypeScript)
+- **`integration-tests/`** - End-to-end Playwright tests
+- **`preprocessing/`** - Sequence and metadata processing pipeline
+- **`ingest/`** - Data ingestion components
+- **`kubernetes/`** - Deployment configurations and Helm charts
+- **`keycloak/`** - Authentication service configuration
+- **`cli/`** - Command-line interface tools
+- **`docs/`** - Documentation website
+
+## Component-Specific Instructions
+
+Each major component has its own `AGENTS.md` file with detailed instructions:
+
+- Backend: [`backend/AGENTS.md`](/backend/AGENTS.md)
+- Website: [`website/AGENTS.md`](/website/AGENTS.md)
+- Integration Tests: [`integration-tests/AGENTS.md`](/integration-tests/AGENTS.md)
+
+Refer to these files for component-specific development guidelines, testing procedures, and best practices.
+
+## Commit Conventions
+
+We follow [conventional commits](https://www.conventionalcommits.org) for all commit messages and PR titles:
+
+- Format: `type(scope): description`
+- Types: `feat`, `fix`, `chore`, `docs`, `test`, `refactor`, `style`, `perf`
+- Scopes (components): `website`, `backend`, `deployment`, `preprocessing`, `ingest`, `deposition`
+- Examples:
+  - `feat(website): add sequence search functionality`
+  - `fix!(backend): [CFG] update database schema`
+  - `chore(deployment): update kubernetes configs`
+
+**Breaking changes:** Mark with `!` (e.g., `feat!:` or `fix!:`). Use `[CFG]` to indicate configuration changes needed in values.yaml.
+
+## Pull Request Requirements
+
+- **Title:** Use conventional commit format
+- **Description:** Write detailed PR summaries, not just bullet points
+- **Testing:** Ensure all tests pass before submitting
+- **Code Style:** Follow the style guidelines for each component
+
+## Testing and Building
+
+### Backend (Kotlin)
+
+```bash
+# Run tests (with Docker)
+./gradlew test --console=plain
+
+# Run tests (without Docker, for cloud environments)
+USE_NONDOCKER_INFRA=true ./gradlew test --console=plain
+
+# Lint/format code
+./gradlew ktlintFormat
+```
+
+Backend tests take considerable time to run. Always ensure tests and lint pass before committing.
+
+### Website (TypeScript/React)
+
+```bash
+# Run tests (important: use CI=1 to prevent watch mode)
+CI=1 npm run test
+
+# Type checking
+npm run check-types
+
+# Format code
+npm run format
+```
+
+**Important:** Always include `CI=1` environment variable when running tests to ensure they run once and exit cleanly instead of staying in watch mode.
+
+### Integration Tests
+
+```bash
+# Format code
+npm run format
+
+# Run tests against specific environment
+PLAYWRIGHT_TEST_BASE_URL=https://main.loculus.org npx playwright test --reporter=list
+
+# Control test execution
+BROWSER=chromium TEST_SUITE=all npx playwright test --workers=4 --reporter=list
+```
+
+See [`integration-tests/AGENTS.md`](/integration-tests/AGENTS.md) for detailed setup instructions for local k3d testing.
+
+## Code Style Guidelines
+
+We value clean code. Follow these principles:
+
+- **Expressive names:** Use clear variable, class, and function names; avoid abbreviations
+- **Small functions and classes:** Keep code modular and focused
+- **Test coverage:** Write tests for all non-trivial code; cover at least the happy path
+- **Testability:** Design code with testing in mind
+- **Generality:** Code should be configurable and suitable for various deployments
+
+## Website-Specific Guidelines
+
+### Preventing Flaky Playwright Tests
+
+When adding or modifying interactive components in the website, ensure they are disabled until React hydration completes to prevent race conditions:
+
+- **For buttons:** Use `Button` from `src/components/common/Button.tsx` instead of native `<button>`
+- **For Headless UI Combobox:** Import from `src/components/common/headlessui/Combobox.tsx` instead of `@headlessui/react`
+- **For other interactive elements:** Wrap with `DisabledUntilHydrated` or use the `useClientFlag` hook
+
+### Website Codemods
+
+For guidance on writing codemods, see [`website/codemods/AGENTS.md`](../website/codemods/AGENTS.md).
+
+## Dependency Management
+
+### Conda Environment Dependencies
+
+Conda dependencies in `environment.yml` files are not automatically updated by Dependabot. Use utilities in the `maintenance-scripts/` folder to help update conda environment versions.
+
+### Security
+
+Always check for security vulnerabilities when adding or updating dependencies. Run security checks before committing.
+
+## OpenAPI Documentation
+
+The backend provides a Swagger UI and OpenAPI specification. Keep the OpenAPI specification accurate and useful when making API changes.
+
+## Authentication
+
+- **Keycloak** is used for authentication
+- Test users are available: `testuser:testuser` and `superuser:superuser`
+- Groups are managed by the backend; each sequence entry is owned by a submitting group
+- See main [README.md](/README.md) for detailed authentication documentation
+
+## Development Workflow
+
+1. **Explore:** Understand the codebase before making changes
+2. **Test locally:** Run relevant tests for the components you modify
+3. **Lint/Format:** Run linters and formatters before committing
+4. **Test coverage:** Ensure new code has appropriate test coverage
+5. **Documentation:** Update docs if needed (OpenAPI specs, README files, etc.)
+6. **PR:** Create a PR with conventional commit title and detailed description
+
+## Additional Resources
+
+- [Main README](/README.md) - Project overview and architecture
+- [Contributing Guide](/CONTRIBUTING.md) - Detailed contribution guidelines
+- [Architecture Docs](/architecture_docs) - System architecture documentation
+- [GitHub Actions](/.github/workflows) - CI/CD workflows
+
+## General Guidelines
+
+- **Minimal changes:** Make the smallest possible changes to achieve the goal
+- **No unrelated fixes:** Don't fix unrelated bugs or broken tests
+- **Preserve working code:** Never delete/modify working code unless absolutely necessary
+- **Security:** Always validate that changes don't introduce security vulnerabilities
+- **Local testing:** Test changes locally before pushing
+- **Docker awareness:** Some tests require Docker; use non-Docker alternatives when unavailable