🐛 Fix annotation edit field overwrite and add IME composition guard

- Conditionally spread only defined fields in handleEditAnnotation
  to prevent undefined values from wiping sibling fields
- Add !e.nativeEvent.isComposing guard to Cmd/Ctrl+Enter handlers
  in comment and suggested-code textareas for CJK input support

Author: flex-yj-kim

packages/review-editor/App.tsx

@@ -290,7 +290,12 @@ const ReviewApp: React.FC = () => {
     originalCode?: string
   ) => {
     setAnnotations(prev => prev.map(ann =>
-      ann.id === id ? { ...ann, text, suggestedCode, originalCode } : ann
+      ann.id === id ? {
+        ...ann,
+        ...(text !== undefined && { text }),
+        ...(suggestedCode !== undefined && { suggestedCode }),
+        ...(originalCode !== undefined && { originalCode }),
+      } : ann
     ));
   }, []);
 

packages/review-editor/components/AnnotationToolbar.tsx

@@ -75,7 +75,7 @@ export const AnnotationToolbar: React.FC<AnnotationToolbarProps> = ({
           onKeyDown={(e) => {
             if (e.key === 'Escape') {
               onDismiss();
-            } else if (e.key === 'Enter' && (e.metaKey || e.ctrlKey)) {
+            } else if (e.key === 'Enter' && (e.metaKey || e.ctrlKey) && !e.nativeEvent.isComposing) {
               onSubmit();
             }
           }}
@@ -107,7 +107,7 @@ export const AnnotationToolbar: React.FC<AnnotationToolbarProps> = ({
               onKeyDown={(e) => {
                 if (e.key === 'Tab') {
                   handleTabIndent(e);
-                } else if (e.key === 'Enter' && (e.metaKey || e.ctrlKey)) {
+                } else if (e.key === 'Enter' && (e.metaKey || e.ctrlKey) && !e.nativeEvent.isComposing) {
                   onSubmit();
                 }
               }}