feat(outliner): prevent creating extra empty block on enter on last empty root bullet

frontend/src/features/workspace/OutlinerTree.tsx

@@ -360,12 +360,14 @@ export const OutlinerTree: React.FC<OutlinerTreeProps> = ({
 
   return (
     <div className="space-y-0.5">
-      {visibleEntries.map(({ block, index, hasChildren, maxAllowedLevel }) => {
+      {visibleEntries.map(({ block, index, hasChildren, maxAllowedLevel }, entryIdx) => {
+        const isLast = entryIdx === visibleEntries.length - 1;
         return (
           <OutlinerBlock
             key={block.id}
             block={block}
             index={index}
+            isLast={isLast}
             maxAllowedLevel={maxAllowedLevel}
             hasChildren={hasChildren}
             isFocused={focusedBlockId === block.id}