feat(android): Add screen context capture for voice assistant

lib/core/utils/android_assistant_handler.dart

@@ -0,0 +1,35 @@
+import 'package:flutter/services.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+final androidAssistantProvider = Provider(
+  (ref) => AndroidAssistantHandler(ref),
+);
+
+final screenContextProvider = NotifierProvider<ScreenContextNotifier, String?>(
+  ScreenContextNotifier.new,
+);
+
+class ScreenContextNotifier extends Notifier<String?> {
+  @override
+  String? build() => null;
+
+  void setContext(String? context) {
+    state = context;
+  }
+}
+
+class AndroidAssistantHandler {
+  static const platform = MethodChannel('app.cogwheel.conduit/assistant');
+  final Ref _ref;
+
+  AndroidAssistantHandler(this._ref) {
+    platform.setMethodCallHandler(_handleMethodCall);
+  }
+
+  Future<void> _handleMethodCall(MethodCall call) async {
+    if (call.method == 'analyzeScreen') {
+      final String context = call.arguments as String;
+      _ref.read(screenContextProvider.notifier).setContext(context);
+    }
+  }
+}