feat(nixos): add pikachu homepage guest

configs/nixos/registry/homepage.nix

@@ -0,0 +1,45 @@
+{ lib, ... }:
+{
+  type = lib.types.submodule {
+    options = {
+      tab = lib.mkOption {
+        type = lib.types.str;
+        example = "Apps";
+        description = "Homepage tab that contains this entry.";
+      };
+
+      section = lib.mkOption {
+        type = lib.types.str;
+        example = "Media";
+        description = "Homepage section that contains this entry.";
+      };
+
+      name = lib.mkOption {
+        type = lib.types.str;
+        example = "Navidrome";
+        description = "Homepage display name for this entry.";
+      };
+
+      description = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        example = "Music";
+        description = "Homepage description for this entry.";
+      };
+
+      icon = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        example = "navidrome.png";
+        description = "Homepage icon for this entry.";
+      };
+
+      href = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        example = "https://music.alexion.dev";
+        description = "Homepage link override for this entry.";
+      };
+    };
+  };
+}