Support external repos

Largely taken from SY.

Co-authored-by: jobobby04 <jobobby04@users.noreply.github.com>

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourceScreenModel.kt

@@ -24,6 +24,8 @@ import eu.kanade.tachiyomi.data.cache.CoverCache
 import eu.kanade.tachiyomi.source.CatalogueSource
 import eu.kanade.tachiyomi.source.model.FilterList
 import eu.kanade.tachiyomi.util.removeCovers
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.emptyFlow
@@ -265,7 +267,10 @@ class BrowseSourceScreenModel(
                 else -> {
                     val preselectedIds = getCategories.await(manga.id).map { it.id }
                     setDialog(
-                        Dialog.ChangeMangaCategory(manga, categories.mapAsCheckboxState { it.id in preselectedIds }),
+                        Dialog.ChangeMangaCategory(
+                            manga,
+                            categories.mapAsCheckboxState { it.id in preselectedIds }.toImmutableList(),
+                        ),
                     )
                 }
             }
@@ -338,7 +343,7 @@ class BrowseSourceScreenModel(
         data class AddDuplicateManga(val manga: Manga, val duplicate: Manga) : Dialog
         data class ChangeMangaCategory(
             val manga: Manga,
-            val initialSelection: List<CheckboxState.State<Category>>,
+            val initialSelection: ImmutableList<CheckboxState.State<Category>>,
         ) : Dialog
         data class Migrate(val newManga: Manga) : Dialog
     }