Add remote database host and update migration SQL

- Added a new remote host configuration to config.php for database connection.
- Updated migration script to ensure proper addition of 'min_order_amount' column in pp_shop_payment_methods table.
- Created .gitignore file to exclude cache directory.
- Added project configuration file for Serena with initial settings and tool configurations.

migrations/0.304.sql

@@ -1,2 +1,2 @@
-ALTER TABLE pp_shop_payment_methods ADD COLUMN min_order_amount DECIMAL(10,2) DEFAULT NULL;
+ALTER TABLE pp_shop_payment_methods ADD COLUMN min_order_amount DECIMAL(10,2) DEFAULT NULL;
 ALTER TABLE pp_shop_payment_methods ADD COLUMN max_order_amount DECIMAL(10,2) DEFAULT NULL;