Fix Simple Mapping to use proper UUIDs for mapping IDs

- Add generateUUID() function using crypto.randomUUID() with fallback
- Update handleAdd to use UUID instead of Date.now() + Math.random()
- UUIDs are now properly validated in backend to prevent injection
- mapping_id is persisted when creating mapping pairs for reuse

Co-authored-by: Koha9 <36852125+Koha9@users.noreply.github.com>

frontend/components/StrategySelector.tsx

@@ -22,6 +22,20 @@ import {
   Code2
 } from 'lucide-react';
 
+// Generate a UUID for mapping rules
+const generateUUID = (): string => {
+  // Use crypto.randomUUID() if available (modern browsers)
+  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
+    return crypto.randomUUID();
+  }
+  // Fallback to manual UUID v4 generation
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+    const r = Math.random() * 16 | 0;
+    const v = c === 'x' ? r : (r & 0x3 | 0x8);
+    return v.toString(16);
+  });
+};
+
 interface StrategyOption {
   value: SyncStrategy;
   label: string;
@@ -137,7 +151,7 @@ const MappingGroupEditor: React.FC<MappingGroupEditorProps> = ({
   
   const handleAdd = () => {
     if (isLocked) return;
-    const newId = Date.now().toString() + Math.random().toString();
+    const newId = generateUUID();
     onChange([...rules, { id: newId, search: '', replace: '' }]);
   };