chore(kotlin/android): add TODO comment (#6813)

Signed-off-by: Reactor Scram <ReactorScram@users.noreply.github.com>

kotlin/android/app/src/main/java/dev/firezone/android/core/data/Repository.kt

@@ -64,6 +64,7 @@ internal class Repository
     ) {
         // We are the only thing that can modify favorites so we shouldn't need to reload it after
         // this initial load
+        // TODO: This should be immutable, we should just replace the hash set on every update
         private val _favorites =
             MutableStateFlow(Favorites(HashSet(sharedPreferences.getStringSet(FAVORITE_RESOURCES_KEY, null).orEmpty())))
         val favorites = _favorites.asStateFlow()