fix: change ScoreRequest json_schema_extra from examples list to example dict

Swagger UI Try it out was sending the {summary, value} wrapper as request body
instead of just the value contents, causing 422 errors. The 'example' (singular)
key is correctly used as the schema-level example by Swagger UI.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

webapp/models.py

@@ -408,10 +408,7 @@ class ScoreRequest(BaseModel):
 
     model_config = ConfigDict(
         json_schema_extra={
-            "examples": [
+            "example": {
-                {
-                    "summary": "基础评分请求",
-                    "value": {
                 "question": "双源CT的时间分辨率是多少?",
                 "answer": "双源CT的单扇区时间分辨率为75ms。",
                 "contexts": "双源CT采用两套管-探测器系统 |||| 单扇区采集旋转135度",
@@ -425,9 +422,7 @@ class ScoreRequest(BaseModel):
                 ],
                 "judge_model": "deepseek-v4-flash",
                 "embedding_model": "text-embedding-v3",
-                    },
             }
-            ]
         }
     )