refactor folder structure

hosts/fw/modules/postgresql.nix

@@ -0,0 +1,20 @@
+{ config, pkgs, ... }:
+
+{
+  services.postgresql = {
+    enable = true;
+    ensureDatabases = [ "mydatabase" ];
+   
+    identMap = ''
+      # ArbitraryMapName systemUser DBUser
+         superuser_map      root      postgres
+         superuser_map      postgres  postgres
+         # Let other names login as themselves
+         superuser_map      /^(.*)$   \1
+    '';
+    authentication = pkgs.lib.mkOverride 10 ''
+      #type database  DBuser  auth-method optional_ident_map
+      local sameuser  all     peer        map=superuser_map
+    '';
+  };
+};