Fix TypeScript build errors

frontend/.env.example

@@ -0,0 +1,23 @@
+# DBIS Admin Console - Environment Variables
+# Copy this file to .env and update with your values
+
+# API Configuration
+# Base URL for the backend API
+VITE_API_BASE_URL=http://localhost:3000
+
+# Application Configuration
+# Display name for the application
+VITE_APP_NAME=DBIS Admin Console
+
+# Real-time Updates
+# Polling interval in milliseconds (default: 5000ms = 5 seconds)
+VITE_REAL_TIME_UPDATE_INTERVAL=5000
+
+# Optional: Error Tracking (Sentry)
+# Uncomment and configure when ready to use error tracking
+# VITE_SENTRY_DSN=your-sentry-dsn-here
+# VITE_SENTRY_ENVIRONMENT=development
+
+# Optional: Feature Flags
+# VITE_ENABLE_WEBSOCKET=false
+# VITE_ENABLE_DARK_MODE=true