Use config from .env and update api

.env.example

@@ -0,0 +1,16 @@
+# Server Configuration
+SERVER_PORT=8080
+GIN_MODE=debug
+
+# Security Configuration
+JWT_SECRET=your-super-secret-jwt-key-here
+
+# Sync Configuration
+SYNC_INTERVAL_MINUTES=1
+
+# Default Admin User Configuration
+ADMIN_EMAIL=admin@admin.com
+ADMIN_PASSWORD=sheetless
+
+# Directory of your sheets
+SHEETS_DIRECTORY=/data/sheets