feat: add configuration files and scripts for project setup ✨

🚀 Breaking Changes:
- Introduced new environment variables for GitLab API integration
- Added validation script for PR checks
- Updated package.json with new scripts for testing and formatting

📝 Details:
- Added .prettierrc and .eslintrc.json for code formatting and linting
- Created .env.example for environment variable setup
- Updated CHANGELOG.md with recent changes
- Added documentation for GitHub secrets setup

docs/setup-github-secrets.md

@@ -0,0 +1,57 @@
+# GitHub Secrets Setup Guide
+
+## 1. Navigate to GitHub Repository
+
+1. Go to your `gitlab-mcp` repository on GitHub
+2. Click on the Settings tab
+3. In the left sidebar, select "Secrets and variables" → "Actions"
+
+## 2. Add Secrets
+
+Click the "New repository secret" button and add the following secrets:
+
+### GITLAB_TOKEN_TEST
+
+- **Name**: `GITLAB_TOKEN_TEST`
+- **Value**: Your GitLab Personal Access Token
+- Used for integration tests to call the real GitLab API
+
+### TEST_PROJECT_ID
+
+- **Name**: `TEST_PROJECT_ID`
+- **Value**: Your test project ID (e.g., `70322092`)
+- The GitLab project ID used for testing
+
+### GITLAB_API_URL (Optional)
+
+- **Name**: `GITLAB_API_URL`
+- **Value**: `https://gitlab.com`
+- Only set this if using a different GitLab instance (default is https://gitlab.com)
+
+## 3. Verify Configuration
+
+To verify your secrets are properly configured:
+
+1. Create a PR or update an existing PR
+2. Check the workflow execution in the Actions tab
+3. Confirm that the "integration-test" job successfully calls the GitLab API
+
+## Security Best Practices
+
+- Never commit GitLab tokens directly in code
+- Grant minimal required permissions to tokens (read_api, write_repository)
+- Rotate tokens regularly
+
+## Local Testing
+
+To run integration tests locally:
+
+```bash
+export GITLAB_TOKEN_TEST="your-token-here"
+export TEST_PROJECT_ID="70322092"
+export GITLAB_API_URL="https://gitlab.com"
+
+npm run test:integration
+```
+
+⚠️ **Important**: When testing locally, use environment variables and never commit tokens to the repository!