fix: skip scroll-based fetch effect in virtualized branch list path

When shouldVirtualizeBranchList is true, branchListScrollElementRef stays
null because setBranchListRef is only attached to the non-virtualized
ComboboxList. The branches.length effect would call maybeFetchNextBranchPage
which bails out immediately due to the null scroll element.

Guard the effect to skip when virtualized, since the LegendList onEndReached
callback already handles infinite loading in that path, and with 40+ items
the visible area is always filled.

Author: cursoragent

apps/web/src/components/BranchToolbarBranchSelector.tsx

@@ -460,8 +460,9 @@ export function BranchToolbarBranchSelector({
   }, [isBranchMenuOpen, maybeFetchNextBranchPage]);
 
   useEffect(() => {
+    if (shouldVirtualizeBranchList) return;
     maybeFetchNextBranchPage();
-  }, [branches.length, maybeFetchNextBranchPage]);
+  }, [branches.length, maybeFetchNextBranchPage, shouldVirtualizeBranchList]);
 
   const triggerLabel = getBranchTriggerLabel({
     activeWorktreePath,