Feat: let image citation being shown. (#7624)

### What problem does this PR solve?

#7623

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

agent/component/retrieval.py

@@ -15,6 +15,7 @@
 #
 import json
 import logging
+import re
 from abc import ABC
 
 import pandas as pd
@@ -59,6 +60,7 @@ class Retrieval(ComponentBase, ABC):
     def _run(self, history, **kwargs):
         query = self.get_input()
         query = str(query["content"][0]) if "content" in query else ""
+        query = re.split(r"(USER:|ASSISTANT:)", query)[-1]
 
         kb_ids: list[str] = self._param.kb_ids or []