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/common/adaptive_root_scaffold.dart

@@ -1,6 +1,7 @@
 import 'package:fluentui_system_icons/fluentui_system_icons.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_adaptive_scaffold/flutter_adaptive_scaffold.dart';
+import 'package:hiddify/gen/assets.gen.dart';
 import 'package:hiddify/core/localization/translations.dart';
 import 'package:hiddify/core/router/router.dart';
 import 'package:hiddify/features/stats/widget/side_bar_stats_overview.dart';
@@ -123,16 +124,15 @@ class _CustomAdaptiveScaffold extends HookConsumerWidget {
                     child: Column(
                       children: [
                         Container(
-                          width: 96,
-                          height: 96,
+                          width: 80,
+                          height: 80,
+                          padding: const EdgeInsets.all(12),
                           decoration: BoxDecoration(
-                            borderRadius: BorderRadius.circular(16),
+                            borderRadius: BorderRadius.circular(20),
                             color: Theme.of(context).colorScheme.primaryContainer,
                           ),
-                          child: Icon(
-                            Icons.shield_outlined,
-                            size: 56,
-                            color: Theme.of(context).colorScheme.primary,
+                          child: Assets.images.umbrixLogo.image(
+                            fit: BoxFit.contain,
                           ),
                         ),
                         const SizedBox(height: 16),