fix: prompt to create or pick folder when archive is missing (#286) (#290)

lib/core/repositories/mailbox_repository.dart

@@ -11,4 +11,13 @@ abstract class MailboxRepository {
 
   /// Deletes all locally-cached mailbox rows for [accountId].
   Future<void> clearForResync(String accountId);
+
+  /// Creates a new mailbox named [name] for [accountId] and tags it with
+  /// [role] in the local database. For JMAP accounts the role is also sent
+  /// to the server. Returns the newly created [Mailbox].
+  Future<Mailbox> createMailboxWithRole(
+    String accountId,
+    String name,
+    String role,
+  );
 }