fix: improve maintenance and synchronize live conversations

backend/app/knowledge/enhanced_pdf_kb.py

@@ -14,9 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 """
 
-from typing import Any, Dict, Iterator, List, Optional
+from typing import Any, Dict, Optional
 from agno.knowledge.pdf import PDFKnowledgeBase
-from agno.document import Document
 from app.core.logger import get_logger
 
 logger = get_logger(__name__)