Mirror the 990-line dropdown in both the group and subcategory edit
dialogs: add form1099BoxId to the frontend group/subcategory DTOs and
request interfaces, load boxes via a new getForm1099Boxes() method on
ExpenseCategoryApiService (same label pattern as getForm990Lines:
"boxCode — name_en / name_zh"), wire form1099BoxId into all
open/edit/save paths, and render a side-by-side "1099 Box / 1099 框"
Kendo DropdownList with [valuePrimitive]="true" and "— none —" default.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Chris Chen
d8e6f3ed61