- Add region column to leaudit_documents + LeauditDocument model
- AuditServiceImpl: read region from document.region, not APP_REGION
- RuleServiceImpl: ListBindings/CreateBinding accept Region parameter
- RuleBindingCreateDTO: add region field
- RuleController: pass region from query param/DTO to service
- APP_REGION removed from binding queries; region flows from document
Region is now per-document: each document carries its region at upload
time, and rules are matched to the document's region at run time.
wren