refactor: bunch of improvements

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

src/types/auxiliary.ts

@@ -22,6 +22,12 @@ export interface JmapAuxiliary {
   
   /** JMAP account ID */
   accountId?: string;
+
+  /** Message delete behavior */
+  deleteMode?: 'soft' | 'hard';
+
+  /** Optional destination mailbox identifier for soft delete */
+  deleteDestination?: string;
   
   /** Allow additional custom fields */
   [key: string]: any;