feat(users): add drag-and-drop reordering for PICs

Introduce pic_sort_order to persist custom user ordering
Replace data table with a custom draggable grid layout
Add API endpoint to handle bulk order updates

shared/auth.ts

@@ -64,6 +64,7 @@ export interface AuthUser {
   fullName: string
   phoneNumber: string | null
   role: UserRole
+  picSortOrder: number
   isActive: boolean
   mustChangePassword: boolean
   needsPasskeySetup: boolean
@@ -81,6 +82,7 @@ export interface PublicContact {
   fullName: string
   phoneNumber: string
   role: UserRole
+  picSortOrder: number
 }
 
 export interface PasskeySummary {