Resolve the app-sidebar.tsx conflict: main refactored the chat-export dropdown to a
format-based CHAT_EXPORT_OPTIONS + dynamic-import exportConversationByFormat dispatcher,
which the merged body already uses. Keep main's dispatcher and drop the branch's static
export imports; keep TestTubeOutlineIcon imported from the shared @/lib/hugeicons-derived
module (also used by images-page) rather than main's duplicate inline definition. The
branch's Images and Video nav items are preserved.