fix: remove get package, upgrade Flutter 3.44 compat deps

- Remove `get` package (incompatible with Flutter 3.44/Dart 3.12 due to
  removed ThemeData.backgroundColor and final IconData class)
- Replace GetMaterialApp → MaterialApp with GlobalKey navigatorKey
- Convert AuthenticationRepository and all 7 controllers from
  GetxController to plain singletons
- Replace Get.snackbar/offAll/to/back/defaultDialog with app_navigator
  helpers and native Flutter APIs
- Add ApiService.baseUrl static + parseJson method
- Add UserModel.getUser static method
- Add UserProvider.score via ScoresModel API
- Fix user?.photo → user?.picture in drawer_menu, service_after
- Fix logout(uid!) → logout() in drawer_menu
- Fix photo_view_web.dart missing dart:typed_data import
- Remove getCoordsOfCity call from ubicacion.dart
- Fix UserModel.getUser?.name null-safety in map/service.dart
- Upgrade: google_maps_flutter ^2.9.0, url_launcher ^6.3.0,
  font_awesome_flutter ^10.8.0, image_picker ^1.1.2

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/src/presentation/screens/cita.dart

@@ -1,8 +1,8 @@
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_rating_bar/flutter_rating_bar.dart';
-import 'package:get/get.dart';
 import 'package:intl/intl.dart';
+import 'package:prosappco/src/utils/app_navigator.dart';
 import 'package:prosappco/src/authentication/authentication_repository.dart';
 import 'package:prosappco/src/components/photo_view.dart';
 import 'package:prosappco/src/components/pop_appbar.dart';
@@ -396,10 +396,10 @@ class _CitaScreenState extends State<CitaScreen> {
                                           ),
                                         );
                                       } else {
-                                        Get.snackbar(
-                                          'El profesional aun no ha aceptado tu solicitud',
-                                          'Debes esperar a que el profesional acepte tu solicitud para poder iniciar un chat.',
-                                          snackPosition: SnackPosition.BOTTOM,
+                                        showAppSnackBar(
+                                          'El profesional aún no ha aceptado',
+                                          'Debes esperar a que el profesional acepte tu solicitud.',
+                                          color: Colors.grey.shade700,
                                         );
                                       }
                                     },