nixos/navidrome: fix settings type

nixos/modules/services/audio/navidrome.nix

@@ -7,7 +7,12 @@
 
 let
   inherit (lib) mkEnableOption mkPackageOption mkOption maintainers;
-  inherit (lib.types) bool str;
+  inherit (lib.types)
+    bool
+    port
+    str
+    submodule
+    ;
   cfg = config.services.navidrome;
   settingsFormat = pkgs.formats.json { };
 in
@@ -20,10 +25,22 @@ in
       package = mkPackageOption pkgs "navidrome" { };
 
       settings = mkOption {
-        type = settingsFormat.type;
-        default = {
-          Address = "127.0.0.1";
-          Port = 4533;
+        type = submodule {
+          freeformType = settingsFormat.type;
+
+          options = {
+            Address = mkOption {
+              default = "127.0.0.1";
+              description = "Address to run Navidrome on.";
+              type = str;
+            };
+
+            Port = mkOption {
+              default = 4533;
+              description = "Port to run Navidrome on.";
+              type = port;
+            };
+          };
         };
         example = {
           MusicFolder = "/mnt/music";