feat: navigation setup.

lib/main.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:revanced_manager_flutter/ui/screens/home_screen.dart';
+import 'package:revanced_manager_flutter/ui/screens/patcher_screen.dart';
+import 'constants.dart';
 
 void main() {
   runApp(const MyApp());
@@ -11,11 +13,70 @@ class MyApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
+      debugShowCheckedModeBanner: false,
       title: 'ReVanced Manager',
-      theme: ThemeData(
-        primarySwatch: Colors.blue,
+      theme: ThemeData.light().copyWith(
+        backgroundColor: Colors.red,
+        useMaterial3: true,
+        colorScheme: const ColorScheme.light(
+          primary: purple40,
+          secondary: purpleGrey40,
+          tertiary: pink40,
+          background: Colors.red,
+        ),
+      ),
+      darkTheme: ThemeData.dark().copyWith(
+        backgroundColor: Colors.red,
+        useMaterial3: true,
+        scaffoldBackgroundColor: const Color(0xff0A0D11),
+        colorScheme: const ColorScheme.dark(
+          primary: purple80,
+          secondary: purpleGrey80,
+          tertiary: pink80,
+          background: Colors.red,
+        ),
+      ),
+      home: const Navigation(),
+    );
+  }
+}
+
+class Navigation extends StatefulWidget {
+  const Navigation({Key? key}) : super(key: key);
+
+  @override
+  State<Navigation> createState() => _NavigationState();
+}
+
+class _NavigationState extends State<Navigation> {
+  int currentPageIndex = 0;
+  final List<Widget> screens = [
+    HomeScreen(),
+    PatcherScreen(),
+  ];
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: screens[currentPageIndex],
+      bottomNavigationBar: NavigationBar(
+        onDestinationSelected: (int index) {
+          setState(() {
+            currentPageIndex = index;
+          });
+        },
+        selectedIndex: currentPageIndex,
+        destinations: const <Widget>[
+          NavigationDestination(
+            icon: Icon(Icons.dashboard),
+            label: "Dashboard",
+          ),
+          NavigationDestination(
+            icon: Icon(Icons.build),
+            label: "Patcher",
+          ),
+        ],
       ),
-      home: const HomeScreen(),
     );
   }
 }