feat: 新增 target description 字段，收紧 id/name 长度，调整延迟列和名称列

src/server/checker/runner/cmd/execute.ts

@@ -187,6 +187,7 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
         exec: t.cmd.exec,
         maxOutputBytes,
       },
+      description: null,
       expect: target.expect as CommandExpectConfig | undefined,
       group: target.group ?? "default",
       id: t.id,