Enhance Docker Compose and NGINX configurations

- Added new environment variables for connection pooling in the .env file.
- Updated Docker Compose to ensure consistent naming conventions for containers and added health checks.
- Increased timeout settings in NGINX configuration for file uploads.
- Improved pgAdmin reverse proxy configuration to handle path rewrites.
- Added migration SQL file and updated helper documentation for database operations.

.env

@@ -7,6 +7,10 @@ DB_NAME="phoenix"
 DB_HOST="phoenixDB"
 DB_PORT=5432
 DB_USERNAME="postgres"
+PHX_SYSTEM_CONNECTION_POOL_MAX=5
+PHX_WORKER_CONNECTION_POOL_MAX=2
+# ===== PGADMIN CONFIGURATION =====
+PGADMIN_DEFAULT_EMAIL="info@phx-erp.de"
 PGADMIN_DEFAULT_EMAIL="info@phx-erp.de"
 MAIL_SERVER="mail.phx-erp.de"
 MAIL_PORT=465
@@ -38,3 +42,4 @@ BILL_BEE_ACTIVE='true'
 CHANNEL_PILOT_PRO_ACTIVE='true'
 # Shopify
 SHOPIFY_ACTIVE='true'
+PHX_HOST_NAME='yuri.phx-erp.de'