refactor(splash): remove unused web splash code and update imports

lib/app/services/splash_remover_stub.dart

@@ -0,0 +1,7 @@
+/// A stub implementation of the splash remover for non-web platforms.
+///
+/// This function does nothing, as splash screen removal is only handled
+/// on the web.
+void removeSplashFromWeb() {
+  // No-op for non-web platforms.
+}

lib/app/services/splash_remover_web.dart

@@ -0,0 +1,6 @@
+import 'dart:js_interop';
+
+/// Web-specific implementation that calls the JavaScript function
+/// to remove the splash screen.
+@JS('removeSplashFromWeb')
+external void removeSplashFromWeb();

lib/app/services/web_splash.dart

@@ -0,0 +1,2 @@
+export 'splash_remover_stub.dart'
+    if (dart.library.html) 'splash_remover_web.dart';

lib/main.dart

@@ -1,6 +1,5 @@
-import 'dart:js_interop';
-
 import 'package:device_preview/device_preview.dart';
+import 'package:flutter_news_app_mobile_client_full_source_code/app/services/web_splash.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/app/config/config.dart';
@@ -9,9 +8,6 @@ import 'package:flutter_news_app_mobile_client_full_source_code/bootstrap.dart';
 // Define the current application environment (production/development/demo).
 const appEnvironment = AppEnvironment.development;
 
-@JS('removeSplashFromWeb')
-external void removeSplashFromWeb();
-
 void main() async {
   final appConfig = switch (appEnvironment) {
     AppEnvironment.production => AppConfig.production(),