feat: Add test deployment workflow and setup documentation

- Implemented a new GitHub Actions workflow for testing deployments (`test-deployment.yml`).
- Created detailed deployment documentation (`DEPLOYMENT-README.md`, `DEPLOYMENT.md`, `QUICK-START.md`) for setting up the testing server and configuring GitHub secrets.
- Added a setup script (`setup-testing-server.sh`) for automating the environment setup on the testing server, including Docker, Nginx, and user configurations.
- Included monitoring and cleanup scripts for managing deployments on the server.

.env.testing.example

@@ -0,0 +1,64 @@
+# Environment Variables for Testing Deployments
+
+# Copy this file to .env in your deployment directory
+
+# ================================
+# APPLICATION SETTINGS
+# ================================
+NODE_ENV=testing
+APP_PORT=3123  # Will be dynamically set to 3000 + PR_NUMBER
+
+# ================================
+# DATABASE CONFIGURATION
+# ================================
+DB_HOST=mariadb
+DB_PORT=3306
+DB_DATABASE=low_code_engine_pr_123  # Will be dynamically set
+DB_USERNAME=app_user
+DB_PASSWORD=your_strong_password_here
+DB_ROOT_PASSWORD=your_strong_root_password_here
+
+# ================================
+# REDIS CONFIGURATION
+# ================================
+REDIS_HOST=redis
+REDIS_PORT=6379
+
+# ================================
+# API TOKENS (if needed)
+# ================================
+# API_TOKEN_SECRET=your_api_token_secret
+# ADMIN_TOKEN=your_admin_token
+
+# ================================
+# EXTERNAL SERVICES (if any)
+# ================================
+# EXTERNAL_API_URL=https://api.example.com
+# EXTERNAL_API_KEY=your_external_api_key
+
+# ================================
+# LOGGING & MONITORING
+# ================================
+LOG_LEVEL=debug
+# SENTRY_DSN=https://your-sentry-dsn@sentry.io/project-id
+
+# ================================
+# PERFORMANCE SETTINGS
+# ================================
+# MAX_CONNECTIONS=100
+# TIMEOUT=30000
+
+# ================================
+# FEATURE FLAGS (if any)
+# ================================
+# ENABLE_FEATURE_X=true
+# ENABLE_DEBUG_MODE=true
+
+# ================================
+# NOTES FOR DEPLOYMENT
+# ================================
+# - This file is automatically generated by GitHub Actions
+# - PR_NUMBER will be substituted with actual PR number
+# - Ports will be calculated as BASE_PORT + PR_NUMBER
+# - Database name will include PR number for isolation
+# - Do not commit this file with real secrets!