Restore accidentally removed files, a few additional import/calculation fixes

inventory-server/dashboard/aircall-server/.env.example

@@ -0,0 +1,21 @@
+# Server Configuration
+NODE_ENV=development
+AIRCALL_PORT=3002
+LOG_LEVEL=info
+
+# Aircall API Credentials
+AIRCALL_API_ID=your_aircall_api_id
+AIRCALL_API_TOKEN=your_aircall_api_token
+
+# Database Configuration
+MONGODB_URI=mongodb://localhost:27017/dashboard
+MONGODB_DB=dashboard
+REDIS_URL=redis://localhost:6379
+
+# Service Configuration
+TIMEZONE=America/New_York
+DAY_STARTS_AT=1 # Business day starts at 1 AM ET
+
+# Optional Settings
+REDIS_TTL=300 # Cache TTL in seconds (5 minutes)
+COLLECTION_NAME=aircall_daily_data