💄 Start working on the UI

- Add bottom NavBar
- Add top bar
- Start working on the `Mixing` Tab

lib/settings_tab.dart

@@ -0,0 +1,27 @@
+import 'package:flutter/material.dart';
+
+class SettingsTab extends StatefulWidget {
+  const SettingsTab({super.key});
+
+  @override
+  State<SettingsTab> createState() => _SettingsTabState();
+}
+
+class _SettingsTabState extends State<SettingsTab> {
+  @override
+  Widget build(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
+    return Card(
+      shadowColor: Colors.transparent,
+      margin: const EdgeInsets.all(8.0),
+      child: SizedBox.expand(
+        child: Center(
+          child: Text(
+            'Settings',
+            style: theme.textTheme.titleLarge,
+          ),
+        ),
+      ),
+    );
+  }
+}