Add accent colour picker, fix empty user card when accepting friend request, add button to transfer allocations

lib/app.dart

@@ -2,8 +2,10 @@ import 'package:flutter/material.dart';
 import 'package:mileograph_flutter/services/api_service.dart';
 import 'package:mileograph_flutter/services/authservice.dart';
 import 'package:mileograph_flutter/services/data_service.dart';
+import 'package:mileograph_flutter/services/accent_color_service.dart';
 import 'package:mileograph_flutter/services/distance_unit_service.dart';
 import 'package:mileograph_flutter/services/endpoint_service.dart';
+import 'package:mileograph_flutter/services/theme_mode_service.dart';
 import 'package:mileograph_flutter/ui/app_shell.dart';
 import 'package:provider/provider.dart';
 
@@ -17,9 +19,15 @@ class App extends StatelessWidget {
         ChangeNotifierProvider<EndpointService>(
           create: (_) => EndpointService(),
         ),
+        ChangeNotifierProvider<AccentColorService>(
+          create: (_) => AccentColorService(),
+        ),
         ChangeNotifierProvider<DistanceUnitService>(
           create: (_) => DistanceUnitService(),
         ),
+        ChangeNotifierProvider<ThemeModeService>(
+          create: (_) => ThemeModeService(),
+        ),
         ProxyProvider<EndpointService, ApiService>(
           update: (_, endpoint, api) {
             final service = api ?? ApiService(baseUrl: endpoint.baseUrl);