chore(splash): use app logo on icon background for native + flutter splash

Replace splash_chat_hebat with assets/icons/logo.png on @color/ic_launcher_background (customer #FF699F pink, mitra #FFFFFF white) across launch_background.xml (x2) and values-v31/styles.xml in both apps; copy logo.png into res/drawable. The mitra Flutter /splash screen still showed the old image — repoint it to assets/icons/logo.png (add assets/icons/ to mitra pubspec), keeping the route (it is the auth-loading gate). Native + flutter splash now match the launcher icon. Old splash_chat_hebat.png left in place but unused.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mitra_app/lib/features/splash/splash_screen.dart

@@ -1,5 +1,9 @@
 import 'package:flutter/material.dart';
 
+/// Loading gate shown by the `/splash` route while auth resolves on launch.
+/// Visually matches the native Android launch splash (new logo on white), so
+/// the user only ever sees one splash with the current icon — no flash of the
+/// old `splash_chat_hebat` image.
 class SplashScreen extends StatelessWidget {
   const SplashScreen({super.key});
 
@@ -9,7 +13,7 @@ class SplashScreen extends StatelessWidget {
       backgroundColor: Colors.white,
       body: Center(
         child: Image.asset(
-          'assets/images/splash_chat_hebat.png',
+          'assets/icons/logo.png',
           width: 200,
         ),
       ),