feat: update home-manager configuration and add custom icon support

- Include icons.nix in home.nix imports for custom icons
- Update Kitty desktop entry to use custom icon path
- Add librsvg and shared-mime-info to GNOME extensions

home-manager/icons.nix

@@ -5,7 +5,9 @@
   xdg.desktopEntries.kitty = {
     name = "Kitty";
     exec = "kitty";
-    icon = "kitty";
+    icon = "${
+      icons.packages.${pkgs.system}.default
+    }/share/icons/hicolor/scalable/apps/custom/kitty.svg";
     terminal = false;
     categories = [
       "System"