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.

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -6,19 +6,25 @@ import FlutterMacOS
 import Foundation
 
 import catcher
-import device_info_plus_macos
+import device_info_plus
+import file_selector_macos
 import flutter_local_notifications
-import package_info_plus_macos
-import path_provider_macos
-import sqflite
+import geolocator_apple
+import package_info_plus
+import path_provider_foundation
+import sqflite_darwin
 import url_launcher_macos
+import webview_flutter_wkwebview
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   CatcherPlugin.register(with: registry.registrar(forPlugin: "CatcherPlugin"))
   DeviceInfoPlusMacosPlugin.register(with: registry.registrar(forPlugin: "DeviceInfoPlusMacosPlugin"))
+  FileSelectorPlugin.register(with: registry.registrar(forPlugin: "FileSelectorPlugin"))
   FlutterLocalNotificationsPlugin.register(with: registry.registrar(forPlugin: "FlutterLocalNotificationsPlugin"))
-  FLTPackageInfoPlusPlugin.register(with: registry.registrar(forPlugin: "FLTPackageInfoPlusPlugin"))
+  GeolocatorPlugin.register(with: registry.registrar(forPlugin: "GeolocatorPlugin"))
+  FPPPackageInfoPlusPlugin.register(with: registry.registrar(forPlugin: "FPPPackageInfoPlusPlugin"))
   PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
   SqflitePlugin.register(with: registry.registrar(forPlugin: "SqflitePlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
+  WebViewFlutterPlugin.register(with: registry.registrar(forPlugin: "WebViewFlutterPlugin"))
 }