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.

nginx/includes/pgadmin.conf

@@ -1,6 +1,6 @@
 # pgAdmin reverse proxy (under subpath)
 location /pgadmin4 {
-    proxy_pass http://pgAdmin4_Ui/;
+    proxy_pass http://pgadmin4-ui/;
     proxy_set_header X-Script-Name /pgadmin4;
     proxy_set_header X-Scheme $scheme;
     proxy_set_header X-Forwarded-Proto $forwarded_proto;
@@ -12,4 +12,7 @@ location /pgadmin4 {
     proxy_set_header X-Forwarded-Proto $forwarded_proto;
     # End of headers
     proxy_redirect off;
+
+    # ⚠️ Rewrite required to remove /pgadmin4 from the path
+    rewrite ^/pgadmin4(/.*)$ $1 break;
 }