feat(app): Koin bootstrap + AppTheme + Material3 XML theme (REDI-84)

- ArchitectureApp.Application: startKoin { androidLogger; androidContext; modules(coreDataModule) }.
  Modules are assembled only here; feature modules will append to the list.
- MainActivity hosts a themed empty screen via AppTheme + AppScaffold (design-system).
- Activity XML theme upgraded to Theme.Material3.DayNight.NoActionBar (Compose themes via AppTheme;
  the Material3 XML theme lets the later Views renderer inherit Material3 styling).
- :app depends on :core:data + :core:design-system; applies the koin convention.

app/src/main/AndroidManifest.xml

@@ -2,6 +2,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
     <application
+        android:name=".ArchitectureApp"
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"