Refactor/message cycle manage and knowledge retrieval (#20460)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/core/rag/entities/citation_metadata.py

@@ -0,0 +1,23 @@
+from typing import Any, Optional
+
+from pydantic import BaseModel
+
+
+class RetrievalSourceMetadata(BaseModel):
+    position: Optional[int] = None
+    dataset_id: Optional[str] = None
+    dataset_name: Optional[str] = None
+    document_id: Optional[str] = None
+    document_name: Optional[str] = None
+    data_source_type: Optional[str] = None
+    segment_id: Optional[str] = None
+    retriever_from: Optional[str] = None
+    score: Optional[float] = None
+    hit_count: Optional[int] = None
+    word_count: Optional[int] = None
+    segment_position: Optional[int] = None
+    index_node_hash: Optional[str] = None
+    content: Optional[str] = None
+    page: Optional[int] = None
+    doc_metadata: Optional[dict[str, Any]] = None
+    title: Optional[str] = None