refactor(sidebar): update sessionMeta handling for session loading logic

- This fixes an issue where the sidebar was showing 6+ even when there were only 5 sessions, due to the hasMore logic not accounting for the case where there are exactly 6 sessions.
It was also showing "Show more sessions" even where there were no more sessions to load.

- This was because `hasMore` was sometimes `undefined` and the logic checked for hasMore !== false, which treated undefined as true.
Now we explicitly check for hasMore === true to determine if there are more sessions to load.

src/hooks/useSidebarController.ts

@@ -324,7 +324,7 @@ export function useSidebarController({
 
   const loadMoreSessions = useCallback(
     async (project: Project) => {
-      const canLoadMore = project.sessionMeta?.hasMore !== false;
+      const canLoadMore = project.sessionMeta?.hasMore === true;
       if (!canLoadMore || loadingSessions[project.name]) {
         return;
       }