fix: correct session reference initialization to prevent dialogue misalignment (#12343)

## Summary

Fixes #12311

Changes the `reference` field initialization from `[{}]` to `[]` in
session creation.

### Problem

When creating a session via the SDK API, the `reference` field was
incorrectly initialized as `[{}]`. This caused:
- First dialogue round: Empty reference
- Second dialogue round: Reference pointing to first round's data
- Overall misalignment between dialogue rounds and their references

### Solution

Changed the initialization to `[]` (empty list), which:
- Matches the `Conversation` model's expected default
- Ensures references grow correctly one-to-one with assistant responses
- Aligns with the service layer's expectations

### Testing

After applying this fix:
1. Create a session via `POST /api/v1/chats/{conversation_id}/sessions`
2. Send multiple questions via `POST
/api/v1/chats/{conversation_id}/completions`
3. View the conversation on web - references should now align correctly
with each dialogue round

api/apps/sdk/session.py

@@ -60,7 +60,7 @@ async def create(tenant_id, chat_id):
         "name": req.get("name", "New session"),
         "message": [{"role": "assistant", "content": dia[0].prompt_config.get("prologue")}],
         "user_id": req.get("user_id", ""),
-        "reference": [{}],
+        "reference": [],
     }
     if not conv.get("name"):
         return get_error_data_result(message="`name` can not be empty.")