feat: Umbrix branding - logo and name changes

- Changed app title from Hiddify to Umbrix in home page
- Added custom Umbrix logo (192x192 PNG)
- Updated intro page with Umbrix branding and gradient design
- Updated drawer menu with Umbrix logo
- Modified add profile modal with modern gradient cards
- Updated Russian translations (appTitle: Umbrix)

lib/features/home/widget/home_page.dart

@@ -36,7 +36,7 @@ class HomePage extends HookConsumerWidget {
                 title: Text.rich(
                   TextSpan(
                     children: [
-                      TextSpan(text: t.general.appTitle),
+                      const TextSpan(text: "Umbrix"),
                       const TextSpan(text: " "),
                       const WidgetSpan(
                         child: AppVersionLabel(),