feat: close modal on successful apply, update design spec

Modal auto-closes after Apply succeeds. Design spec updated to reflect
implemented behavior: local-edit-then-apply pattern, target select
dropdowns, amber pill for add-to-group, close-on-success.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/Admin/ClaimMappingRulesModal.tsx

@@ -229,8 +229,8 @@ export default function ClaimMappingRulesModal({ open, onClose }: Props) {
         }
       }
 
-      setDirty(false);
       toast({ title: 'Rules saved', variant: 'success' });
+      handleClose();
     } catch (e: any) {
       toast({ title: 'Failed to save rules', description: e.message, variant: 'error', duration: 86_400_000 });
     } finally {