feat: add P7 OCR soak scenario and scoreboard

src/polygateway/ocr.py

@@ -404,13 +404,18 @@ class OcrClient:
                 source_name=source.name,
                 usage_source="measured",
             )
+        # 错误带异常类名前缀(metric ocr-call-success 注册口径: 按类名归组)
+        if error is None or isinstance(error, str):
+            error_text = error
+        else:
+            error_text = f"{type(error).__name__}: {error}"
         await self._emitter.emit_attempt(
             request=request,
             source=source,
             call_id=call_id,
             latency_ms=latency_ms,
             response=response,
-            error=None if error is None else str(error),
+            error=error_text,
         )
 
     @staticmethod