✨ Auto complete, better metion parser, sticker placeholder v2

lib/services/autocomplete_service.dart

@@ -0,0 +1,28 @@
+import 'package:dio/dio.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:island/models/autocomplete_response.dart';
+import 'package:island/pods/network.dart';
+
+final autocompleteServiceProvider = Provider<AutocompleteService>((ref) {
+  final dio = ref.watch(apiClientProvider);
+  return AutocompleteService(dio);
+});
+
+class AutocompleteService {
+  final Dio _client;
+
+  AutocompleteService(this._client);
+
+  Future<List<AutocompleteSuggestion>> getSuggestions(
+    String roomId,
+    String content,
+  ) async {
+    final response = await _client.post(
+      '/sphere/chat/$roomId/autocomplete',
+      data: {'content': content},
+    );
+
+    final data = response.data as List<dynamic>;
+    return data.map((json) => AutocompleteSuggestion.fromJson(json)).toList();
+  }
+}