feat: Phase 2 — upgrade deps to null-safe, replace deprecated packages

- pubspec: bump all maintained deps to null-safe latest; flutter pub get resolves
- Remove 12 packages (0-ref or no null-safe): splashscreen, flappy_search_bar,
  searchable_dropdown, share, platform_detect, flutter_inappwebview, countdown,
  gender_selection, flutter_dash, smooth_star_rating, hovering, ffi
- Add flutter_rating_bar
- Keep discontinued-but-null-safe for now (Phase 5): pull_to_refresh, hive, catcher
- New null-safe custom components (API-compatible, callers change only imports):
  utils/countdown.dart, widgets/general/{hover_widget,gender_selection,
  smooth_star_rating,search_bar}.dart
- main.dart: drop dead SplashScreen _buildBody + _to field
- 23 consuming files: swap deprecated imports to local components

Null-safety migration + upgraded-API adaptation = Phase 3.

lib/widgets/desktop/desktop_change_mobile_or_email.dart

@@ -1,6 +1,6 @@
 
 
-import 'package:countdown/countdown.dart';
+import '../../utils/countdown.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';

lib/widgets/desktop/desktop_edit_address.dart

@@ -5,7 +5,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_spinkit/flutter_spinkit.dart';
 import 'package:flutter_wisetronic/widgets/general/breadcrumbs.dart';
 import 'package:fluttertoast/fluttertoast.dart';
-import 'package:gender_selection/gender_selection.dart';
+import '../general/gender_selection.dart';
 
 import '../../constants.dart';
 import '../../events/eventbus.dart';

lib/widgets/desktop/desktop_forgot_password.dart

@@ -1,5 +1,5 @@
 
-import 'package:countdown/countdown.dart';
+import '../../utils/countdown.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_wisetronic/widgets/general/breadcrumbs.dart';

lib/widgets/desktop/desktop_new_address.dart

@@ -2,7 +2,7 @@
 import 'package:email_validator/email_validator.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_wisetronic/widgets/general/breadcrumbs.dart';
-import 'package:gender_selection/gender_selection.dart';
+import '../general/gender_selection.dart';
 
 import '../../constants.dart';
 import '../../generated/l10n.dart';

lib/widgets/desktop/desktop_new_comment.dart

@@ -5,7 +5,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_wisetronic/widgets/general/breadcrumbs.dart';
 import 'package:flutter_wisetronic/widgets/general/navigationbar.dart';
 import 'package:percent_indicator/linear_percent_indicator.dart';
-import 'package:smooth_star_rating/smooth_star_rating.dart';
+import '../general/smooth_star_rating.dart';
 
 import '../../constants.dart';
 import '../../events/eventbus.dart';

lib/widgets/desktop/desktop_new_user.dart

@@ -1,5 +1,5 @@
 
-import 'package:countdown/countdown.dart';
+import '../../utils/countdown.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:fluttertoast/fluttertoast.dart';

lib/widgets/desktop/desktop_search_place.dart

@@ -1,6 +1,6 @@
 
 import 'package:dio/dio.dart';
-import 'package:flappy_search_bar/flappy_search_bar.dart';
+import '../general/search_bar.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_wisetronic/widgets/general/breadcrumbs.dart';
 import 'package:flutter_wisetronic/widgets/general/navigationbar.dart';

lib/widgets/desktop/desktop_store_product_search.dart

@@ -1,6 +1,6 @@
 
 import 'package:dio/dio.dart';
-import 'package:flappy_search_bar/flappy_search_bar.dart';
+import '../general/search_bar.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_wisetronic/pages/product_detail_page.dart';

lib/widgets/desktop/product_item.dart

@@ -1,6 +1,6 @@
 
 import 'package:flutter/material.dart';
-import 'package:hovering/hovering.dart';
+import '../general/hover_widget.dart';
 
 import '../../events/eventbus.dart';
 import '../../events/events.dart';

lib/widgets/desktop/product_search.dart

@@ -1,6 +1,6 @@
 
 import 'package:dio/dio.dart';
-import 'package:flappy_search_bar/flappy_search_bar.dart';
+import '../general/search_bar.dart';
 import 'package:flutter/material.dart';
 
 import '../../constants.dart';