fix(desktop): DeerFlow UI — ChatArea refactor + ai-elements + dead CSS cleanup

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>

desktop/src/store/index.ts

@@ -55,6 +55,17 @@ export type {
   SessionOptions,
 } from '../components/BrowserHand/templates/types';
 
+// === Classroom Store ===
+export { useClassroomStore } from './classroomStore';
+export type {
+  ClassroomState,
+  ClassroomActions,
+  ClassroomStore,
+  GenerationRequest,
+  GenerationResult,
+  GenerationProgressEvent,
+} from './classroomStore';
+
 // === Store Initialization ===
 
 import { getClient } from './connectionStore';