refactor(i18n): U37 全量 JSX 文本节点硬编码中文清零 — 65 文件 151 处→0, 新增 common.* 98 翻译键, zh/en 对齐, tsc -b=0, npm build✓ (17.96s), ESLint=0/43/any=0, go build=0, 17/17 测试通过

frontend/src/components/agent/AgentAlerts.tsx

@@ -273,9 +273,9 @@ export function AgentAlerts() {
                                 </span>
                               )}
                               {rule.metric === 'port_down' && rule.port ? (
-                                <span className="dg-text-secondary">端口 {rule.port}</span>
+                                <span className="dg-text-secondary">{i18n.t("common.port")} {rule.port}</span>
                               ) : null}
-                              {rule.duration ? <span className="dg-text-secondary">持续 {rule.duration}s</span> : null}
+                              {rule.duration ? <span className="dg-text-secondary">{i18n.t("common.duration")} {rule.duration}s</span> : null}
                             </div>
                           </div>
                         </div>