feat(10-01): KB ingestion pipeline - migration, extractors, API router

- Migration 014: add status/error_message/chunk_count to kb_documents, make agent_id nullable
- Add GOOGLE_CALENDAR to ChannelTypeEnum in tenant.py
- Add brave_api_key, firecrawl_api_key, google_client_id/secret, minio_kb_bucket to config
- Add text extractors for PDF, DOCX, PPTX, XLSX/XLS, CSV, TXT, MD
- Add KB management API router with upload, list, delete, URL ingest, reindex endpoints
- Install pypdf, python-docx, python-pptx, openpyxl, pandas, firecrawl-py, youtube-transcript-api
- Update .env.example with new env vars
- Unit tests: test_extractors.py (10 tests) and test_kb_upload.py (7 tests) all pass

.env.example

@@ -62,6 +62,21 @@ DEBUG=false
 # Tenant rate limits (requests per minute defaults)
 DEFAULT_RATE_LIMIT_RPM=60
 
+# -----------------------------------------------------------------------------
+# Web Search / Knowledge Base Scraping
+# BRAVE_API_KEY: Get from https://brave.com/search/api/
+# FIRECRAWL_API_KEY: Get from https://firecrawl.dev
+# -----------------------------------------------------------------------------
+BRAVE_API_KEY=
+FIRECRAWL_API_KEY=
+
+# Google OAuth (Calendar integration)
+GOOGLE_CLIENT_ID=
+GOOGLE_CLIENT_SECRET=
+
+# MinIO KB bucket (for knowledge base documents)
+MINIO_KB_BUCKET=kb-documents
+
 # -----------------------------------------------------------------------------
 # Web Push Notifications (VAPID keys)
 # Generate with: cd packages/portal && npx web-push generate-vapid-keys