treewide: impermanence configuration

hosts/vps1/photoprism.nix

@@ -32,6 +32,14 @@ in
     file = "${inputs.secrets}/passwords/services/photoprism/admin.age";
   };
 
+  environment.persistence."/persist".directories = [
+    {
+      directory = "/var/lib/private/photoprism";
+      user = "photoprism";
+      group = "photoprism";
+    }
+  ];
+
   services.photoprism = {
     enable = true;
     address = "localhost";