Replace inline SVG whiteboard rendering in SceneRenderer with the dedicated WhiteboardCanvas component, gaining chart/latex support and eliminating 27 lines of duplicated rendering logic.
ChatArea retry button uses setInput instead of direct sendToGateway, fix bootstrap spinner stuck for non-logged-in users, remove dead CSS (aurora-title/sidebar-open/quick-action-chips), add ai components (ReasoningBlock/StreamingText/ChatMode/ModelSelector/TaskProgress), add ClassroomPlayer + ResizableChatLayout + artifact panel Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
