feat(characters): Koin module + nav graph + wire into :app (REDI-89)

- charactersPresentationModule: viewModelOf(::CharacterListViewModel) (in the UI-agnostic module).
- @Serializable CharacterListRoute + NavGraphBuilder.charactersGraph { composable<CharacterListRoute> }
  in presentation-compose (serialization plugin added for type-safe routes).
- :app registers coreDataModule + charactersDataModule + charactersPresentationModule in startKoin,
  and hosts a NavHost(startDestination = CharacterListRoute) calling charactersGraph.
- core:data manifest declares INTERNET (merges into :app) for live API calls.

feature/characters/presentation-compose/build.gradle.kts

@@ -1,5 +1,7 @@
 plugins {
     alias(libs.plugins.architecture.android.feature)
+    // For @Serializable type-safe navigation routes.
+    alias(libs.plugins.architecture.kotlinx.serialization)
 }
 
 android {