Remove notification service and update project

- Remove flutter_local_notifications dependency from pubspec.yaml
- Delete notification_service.dart file
- Remove notification service references from app_service.dart and app_binding.dart
- Clean up related code and dependencies

android/app/build.gradle.kts

@@ -13,6 +13,7 @@ android {
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_11
         targetCompatibility = JavaVersion.VERSION_11
+        isCoreLibraryDesugaringEnabled = true
     }
 
     kotlinOptions {
@@ -42,3 +43,7 @@ android {
 flutter {
     source = "../.."
 }
+
+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.0.4")
+}