refactor(deck-picker): move deck selection to ViewModel

Assisted-by: Claude Opus 4.6

Author: david-allison

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt

@@ -451,10 +451,9 @@ open class DeckPicker :
 
     private fun showDeckPickerContextMenu(deckId: DeckId) =
         launchCatchingTask {
-            withCol { decks.select(deckId) }
+            viewModel.selectDeck(deckId).join()
             val menu = DeckPickerContextMenu.newInstance(deckId)
             CardBrowser.clearLastDeckId()
-            updateDeckList()
             showDialogFragment(menu)
         }
 
@@ -463,8 +462,7 @@ open class DeckPicker :
         x: Float,
         y: Float,
     ) = launchCatchingTask {
-        withCol { decks.select(deckId) }
-        updateDeckList()
+        viewModel.selectDeck(deckId).join()
         DeckPickerMenuContentProvider.show(
             deckPicker = this@DeckPicker,
             deckId = deckId,

AnkiDroid/src/main/java/com/ichi2/anki/deckpicker/DeckPickerViewModel.kt

@@ -275,6 +275,17 @@ class DeckPickerViewModel :
             flowOfDeckCountsChanged.emit(Unit)
         }
 
+    /**
+     * Marks [deckId] as the currently selected deck and updates the selection in the deck list.
+     */
+    fun selectDeck(deckId: DeckId) =
+        viewModelScope.launch {
+            // TODO: should we always reset the Card Browser default deck here?
+            withCol { decks.select(deckId) }
+            focusedDeck = deckId
+            flowOfRefreshDeckList.emit(Unit)
+        }
+
     fun browseCards(deckId: DeckId) =
         launchCatchingIO {
             withCol { decks.select(deckId) }