fix: use loose inequality for thread.branch null check to handle undefined thread

When thread is undefined (from useSidebarThreadSummaryById), thread?.branch
evaluates to undefined. With strict inequality (!== null), undefined !== null
is true, causing useGitStatus to receive a non-null gitCwd for a non-existent
thread. Switch to loose inequality (!= null) to correctly handle both null
and undefined.

Author: cursoragent

apps/web/src/components/Sidebar.tsx

@@ -298,7 +298,7 @@ function SidebarThreadRow(props: SidebarThreadRowProps) {
       selectThreadTerminalState(state.terminalStateByThreadId, props.threadId).runningTerminalIds,
   );
   const gitCwd = thread?.worktreePath ?? props.projectCwd;
-  const gitStatus = useGitStatus(thread?.branch !== null ? gitCwd : null);
+  const gitStatus = useGitStatus(thread?.branch != null ? gitCwd : null);
 
   if (!thread) {
     return null;