refactor: Update MainActivity for edge-to-edge display support

- Implemented modern edge-to-edge display handling for Android 15+ in MainActivity.kt.
- Removed deprecated SystemUiMode.edgeToEdge configuration from main.dart, as edge-to-edge is now managed natively.
- Ensured backward compatibility by maintaining the previous edge-to-edge display settings for lower Android versions.

android/app/src/main/kotlin/app/cogwheel/conduit/MainActivity.kt

@@ -10,10 +10,15 @@ class MainActivity : FlutterActivity() {
     private lateinit var backgroundStreamingHandler: BackgroundStreamingHandler
     
     override fun onCreate(savedInstanceState: Bundle?) {
-        // Ensure content draws behind system bars (backwards compatible helper)
-        WindowCompat.setDecorFitsSystemWindows(window, false)
-        
         super.onCreate(savedInstanceState)
+        
+        // Modern edge-to-edge implementation for Android 15+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.VANILLA_ICE_CREAM) {
+            window.decorView.setOnApplyWindowInsetsListener(null)
+        }
+        
+        // Enable edge-to-edge display (backwards compatible)
+        WindowCompat.setDecorFitsSystemWindows(window, false)
     }
     
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {

lib/main.dart

@@ -1,7 +1,6 @@
 import 'dart:async';
 import 'dart:developer' as developer;
 import 'package:flutter/material.dart';
-import 'package:flutter/services.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'core/widgets/error_boundary.dart';
@@ -56,12 +55,9 @@ void main() {
       _startupTimeline!.start('app_startup');
       _startupTimeline!.instant('bindings_initialized');
 
-      // Defer edge-to-edge mode to post-frame to avoid impacting first paint
-      WidgetsBinding.instance.addPostFrameCallback((_) {
-        // ignore: discarded_futures
-        SystemChrome.setEnabledSystemUIMode(SystemUiMode.edgeToEdge);
-        _startupTimeline?.instant('edge_to_edge_enabled');
-      });
+      // Edge-to-edge is now handled natively in MainActivity.kt for Android 15+
+      // No need for SystemUiMode.edgeToEdge which is deprecated
+      _startupTimeline?.instant('edge_to_edge_configured');
 
       const secureStorage = FlutterSecureStorage(
         aOptions: AndroidOptions(