Add error handling for configuration loading at application startup.
If the config file is missing or invalid, the app will exit with
a clear error message instead of crashing later.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Add box schemas (BoxInfoResponse, BoxSaveRequest, BoxSaveResponse)
- Add box service with ERP view query and save logic (supports many2one append)
- Add box router with GET /box/info and POST /box endpoints
- Register exception handlers for InvalidZongpaiError, ZongpaiNotFoundError, DuplicateBoxItemError
- Update RequestValidationError handler to cover INVALID_BOX_NO and INVALID_QUANTITY
- Add 7 integration tests for box API
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
