feat(services): add dedicated PostgreSQL module

Introduce a dedicated PostgreSQL configuration module to the system. Adjust Nextcloud and Forgejo configurations to utilize this new module.

systems/x86_64-linux/mx/nextcloud.nix

@@ -5,6 +5,7 @@
   environment.systemPackages = with pkgs; [ ffmpeg ];
 
   environment.etc."nextcloud-admin-pass".text = "test123";
+
   services.nextcloud = {
     enable = true;
     package = pkgs.nextcloud30;
@@ -44,4 +45,16 @@
       "OC\\Preview\\XBitmap"
     ];
   };
+
+  services.postgresql = {
+    ensureDatabases = [
+      "nextcloud"
+    ];
+    ensureUsers = [
+      {
+        name = "nextcloud";
+        ensureDBOwnership = true;
+      }
+    ];
+  };
 }