refactor(i18n): U21 Zabbix 组件 i18n 治理 — ZabbixDatasourceManager + ZabbixDashboard 从 i18n.t() 全局改为 useTranslation() hook

- ZabbixDatasourceManager.tsx (415L): 30 处 i18n.t()/硬编码中文清零, 删除 5 个 monitor.zabbixdatasourc.* hash 键, 新增 monitor.zabbixDs.* 语义化命名空间 (23 键)
- ZabbixDashboard.tsx (162L): 12 处 i18n.t()/硬编码中文清零, 删除 monitor.zabbixdashboard.* + monitor.prometheusdashb.s5e8eb212 hash 键, 修复 3 个中文幻影键 (i18n.t('磁盘') → t('monitor.zabbixDs.disk') 等)
- 新增 common.days/common.seconds 通用单位键
- 删除 monitor.zabbixdatasourc (5 hash 键) + monitor.zabbixdashboard (1 hash 键) + monitor.prometheusdashb.s5e8eb212 hash 键
- zh/en 6767=6767 对齐, tsc -b=0, npm build✓ (17.41s), ESLint=0/43/0/0, go build=0, 17/17 测试通过

frontend/src/locales/zh-CN.json

@@ -511,7 +511,9 @@
     "created": "已创建",
     "severity": "级别",
     "critical": "严重",
-    "request.tokenExpired": "登录已过期，请重新登录"
+    "request.tokenExpired": "登录已过期，请重新登录",
+    "days": "天",
+    "seconds": "秒"
   },
   "menu": {
     "dashboard": "仪表盘",
@@ -4393,6 +4395,41 @@
       "wechat": "企业微信",
       "email": "邮件",
       "sms": "短信"
+    },
+    "zabbixDs": {
+      "title": "Zabbix 数据源",
+      "subtitle": "配置 Zabbix API 连接，获取主机监控数据",
+      "addDatasource": "添加数据源",
+      "emptyState": "暂无 Zabbix 数据源",
+      "fetchListError": "获取数据源列表失败",
+      "urlRequired": "请输入 Zabbix API URL",
+      "datasourceSaved": "数据源已保存",
+      "deleteConfirm": "确定删除「{{name}}」？",
+      "setDefaultSuccess": "已将「{{name}}」设为默认",
+      "deleteFailed": "删除失败",
+      "editTitle": "编辑 Zabbix 数据源",
+      "createTitle": "新建 Zabbix 数据源",
+      "dialogDesc": "配置 Zabbix API 连接，用于主机监控与告警数据获取",
+      "namePlaceholder": "如：生产 Zabbix",
+      "apiAuth": "Zabbix API 认证",
+      "trendsSettings": "Trends 设置",
+      "otherSettings": "其他设置",
+      "directDbBadge": "直连DB",
+      "disableAck": "只读用户禁用确认",
+      "disableDataAlignment": "禁用数据对齐",
+      "testConnection": "测试连接",
+      "user": "用户",
+      "loading": "加载中...",
+      "noHosts": "未找到被监控的 Zabbix 主机",
+      "hostMonitor": "Zabbix 主机监控",
+      "unit": "台",
+      "disk": "磁盘",
+      "flowOut": "流出",
+      "problems": "问题",
+      "totalHosts": "共 {{count}} 台主机",
+      "perPage": "/页",
+      "prevPage": "上一页",
+      "nextPage": "下一页"
     }
   },
   "task": {