fix: attach custom study dialog factory in SingleFragmentActivity

this avoids a lifecycle crash where SingleFragmentActivity may
crash on activity-recreation if it is hosting the CongratsPage which
hosts the CustomStudyDialog, since CustomStudyDialog fragment does
not have a default constructor - it strictly requires its custom
factory to be installed

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

@@ -19,11 +19,15 @@ import android.content.Context
 import android.content.Intent
 import android.os.Bundle
 import android.view.KeyEvent
+import androidx.fragment.app.DialogFragment
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentContainerView
 import androidx.fragment.app.commit
 import com.ichi2.anki.android.input.ShortcutGroup
 import com.ichi2.anki.android.input.ShortcutGroupProvider
+import com.ichi2.anki.dialogs.customstudy.CustomStudyDialog
+import com.ichi2.anki.dialogs.customstudy.CustomStudyDialogFactory
+import com.ichi2.utils.ExtendedFragmentFactory
 import com.ichi2.utils.getInstanceFromClassName
 import timber.log.Timber
 import kotlin.reflect.KClass
@@ -38,14 +42,21 @@ import kotlin.reflect.jvm.jvmName
  *
  * [getIntent] can be used as an easy way to build a [SingleFragmentActivity]
  */
-open class SingleFragmentActivity : AnkiActivity() {
+open class SingleFragmentActivity : AnkiActivity(), CustomStudyDialog.CustomStudyListener {
     /** The displayed fragment. */
     lateinit var fragment: Fragment
 
     override fun onCreate(savedInstanceState: Bundle?) {
         if (showedActivityFailedScreen(savedInstanceState)) {
             return
         }
+
+        // This page *may* host the CustomStudyDialog (CongratsPage)
+        // CustomStudyDialog requires a custom factory install during lifecycle or it can
+        // crash during lifecycle resume after background kill
+        val customStudyDialogFactory = CustomStudyDialogFactory({ this.getColUnsafe }, this)
+        customStudyDialogFactory.attachToActivity<ExtendedFragmentFactory>(this)
+
         super.onCreate(savedInstanceState)
         if (!ensureStoragePermissions()) {
             return
@@ -101,6 +112,41 @@ open class SingleFragmentActivity : AnkiActivity() {
 
     override val shortcuts: ShortcutGroup?
         get() = (fragment as? ShortcutGroupProvider)?.shortcuts
+
+    // Begin - implementation of CustomStudyListener methods here for crash fix
+    // TODO - refactor https://github.com/ankidroid/Anki-Android/pull/17508#pullrequestreview-2465561993
+    private fun openStudyOptionsAndFinish() {
+        val intent = Intent(this, StudyOptionsActivity::class.java).apply {
+            putExtra("withDeckOptions", false)
+        }
+        startActivity(intent, null)
+        this.finish()
+    }
+
+    override fun onExtendStudyLimits() {
+        Timber.v("CustomStudyListener::hideProgressBar() - not handled")
+        openStudyOptionsAndFinish()
+    }
+
+    override fun showDialogFragment(newFragment: DialogFragment) {
+        Timber.v("CustomStudyListener::showDialogFragment()")
+        newFragment.show(supportFragmentManager, null)
+    }
+
+    override fun startActivity(intent: Intent) {
+        Timber.v("CustomStudyListener::startActivity() - not handled")
+    }
+
+    override fun onCreateCustomStudySession() {
+        Timber.v("CustomStudyListener::onCreateCustomStudySession()")
+        openStudyOptionsAndFinish()
+    }
+
+    override fun hideProgressBar() {
+        Timber.v("CustomStudyListener::hideProgressBar() - not handled")
+    }
+
+    // END CustomStudyListener temporary implementation - should refactor out
 }
 
 interface DispatchKeyEventListener {