feat(workspace): recursive folder tree, link modal redesign, todo grouping & line jumping, hashtag child listing

frontend/src/features/workspace/OutlinerBlock.tsx

@@ -63,6 +63,7 @@ export interface OutlinerBlockProps {
   onDragOverBlock?: (e: React.DragEvent, index: number) => void;
   onDropBlock?: (index: number) => void;
   isDragTarget?: boolean;
+  isTargeted?: boolean;
   registerTextareaRef: (blockId: string, el: HTMLTextAreaElement | null) => void;
 }
 
@@ -88,6 +89,7 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
   onDragOverBlock,
   onDropBlock,
   isDragTarget,
+  isTargeted,
   registerTextareaRef,
 }) => {
   const [localContent, setLocalContent] = useState<string>(block.content || '');
@@ -439,9 +441,11 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
 
   return (
     <div
-      className={`group relative flex items-start gap-1 py-1 rounded-card transition-colors ${
+      className={`group relative flex items-start gap-1 py-1 rounded-card transition-all duration-300 ${
         isDragTarget
           ? 'border-t-2 border-accent bg-accent/10'
+          : isTargeted
+          ? 'bg-accent/15 ring-2 ring-accent'
           : isFocused
           ? 'bg-panel-elevated'
           : 'hover:bg-panel'