feat: add streaming learning assistant and knowledge base scaffolding

app/tasks/knowledge_ingestion_tasks.py

@@ -0,0 +1,13 @@
+import asyncio
+
+from app.db.session import SessionLocal
+from app.services.document_ingestion_service import DocumentIngestionService
+from app.tasks.celery_app import celery_app
+
+
+@celery_app.task(name="knowledge.ingest_document")
+def ingest_knowledge_document(document_id: int, task_id: int) -> None:
+    """知识库异步任务：在 Celery worker 中执行 PDF 解析和向量入库。"""
+    with SessionLocal() as db:
+        asyncio.run(DocumentIngestionService(db).ingest_document(document_id, task_id))
+        db.commit()