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/ai/services/document-extraction.service.ts

@@ -0,0 +1,56 @@
+import fs from 'fs'
+import path from 'path'
+import * as pdfjsLib from 'pdfjs-dist/legacy/build/pdf.mjs'
+
+if (typeof pdfjsLib.GlobalWorkerOptions !== 'undefined') {
+  pdfjsLib.GlobalWorkerOptions.workerSrc = path.join(
+    process.cwd(),
+    'node_modules/pdfjs-dist/legacy/build/pdf.worker.mjs'
+  )
+}
+
+interface ExtractedPage {
+  pageNumber: number
+  text: string
+}
+
+export interface ExtractedDocument {
+  pages: ExtractedPage[]
+  totalPages: number
+  metadata: { title?: string; author?: string }
+}
+
+export class DocumentExtractionService {
+  async extractPdf(filePath: string): Promise<ExtractedDocument> {
+    const dataBuffer = fs.readFileSync(filePath)
+    const doc = await pdfjsLib.getDocument({
+      data: new Uint8Array(dataBuffer),
+      useSystemFonts: true,
+      useWorkerFetch: false,
+      isEvalSupported: false,
+    }).promise
+
+    const pages: ExtractedPage[] = []
+    for (let i = 1; i <= doc.numPages; i++) {
+      const page = await doc.getPage(i)
+      const content = await page.getTextContent()
+      const text = content.items
+        .map((item: any) => item.str)
+        .join(' ')
+      pages.push({ pageNumber: i, text })
+    }
+
+    const metadata = await doc.getMetadata().catch(() => null) as any
+
+    return {
+      pages,
+      totalPages: doc.numPages,
+      metadata: {
+        title: metadata?.info?.Title,
+        author: metadata?.info?.Author,
+      },
+    }
+  }
+}
+
+export const documentExtractionService = new DocumentExtractionService()