feat: brainstorm sessions, PDF document Q&A, embedding fixes, and UI improvements

- Add brainstorm feature with collaborative canvas, AI idea generation, live cursors, playback, and export
- Add PDF upload/extraction/ingestion pipeline with pgvector document search (RAG)
- Add document Q&A overlay with streaming chat and PDF preview
- Add note attachments UI with status polling, grid layout, and auto-scroll
- Add task extraction AI tool and agent executor improvements
- Fix NoteEmbedding missing updatedAt column, re-index 66 notes with 1536-dim embeddings
- Fix brainstorm 'Create Note' button: add success toast and redirect to created note
- Fix memory echo notification infinite polling
- Fix chat route to always include document_search tool
- Add brainstorm i18n keys across all 14 locales
- Add socket server for real-time brainstorm collaboration
- Add hierarchical notebook selector and organize notebook dialog improvements
- Add sidebar brainstorm section with session management
- Update prisma schema with brainstorm tables, attachments, and document chunks

memento-note/lib/query-keys.ts

@@ -18,6 +18,11 @@ export const queryKeys = {
   aiSettings: (userId: string) => ['ai', 'settings', userId] as const,
   titleSuggestions: (content: string) => ['ai', 'title-suggestions', content] as const,
   autoTags: (content: string, notebookId?: string | null) => ['ai', 'auto-tags', content, notebookId] as const,
+
+  // Brainstorm
+  brainstormSessions: () => ['brainstorm', 'sessions'] as const,
+  brainstormSharedSessions: () => ['brainstorm', 'shared-sessions'] as const,
+  brainstormSession: (sessionId: string) => ['brainstorm', 'session', sessionId] as const,
 } as const
 
 export type QueryKeys = typeof queryKeys