fix(ops): 优化错误日志查询和详情展示

- 新增 GetErrorLogByID 接口用于获取单个错误日志详情
- 优化 GetErrorLogs 过滤逻辑，简化参数处理
- 简化前端错误详情模态框代码，提升可维护性
- 更新相关 API 接口和 i18n 翻译

backend/internal/server/routes/admin.go

@@ -123,6 +123,7 @@ func registerOpsRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		// Request errors (client-visible failures)
 		ops.GET("/request-errors", h.Admin.Ops.ListRequestErrors)
 		ops.GET("/request-errors/:id", h.Admin.Ops.GetRequestError)
+		ops.GET("/request-errors/:id/upstream-errors", h.Admin.Ops.ListRequestErrorUpstreamErrors)
 		ops.POST("/request-errors/:id/retry-client", h.Admin.Ops.RetryRequestErrorClient)
 		ops.POST("/request-errors/:id/upstream-errors/:idx/retry", h.Admin.Ops.RetryRequestErrorUpstreamEvent)
 		ops.PUT("/request-errors/:id/resolve", h.Admin.Ops.ResolveRequestError)