fix(web): stop spurious page refresh on account menu open; plugin log auto-refresh as switch

Two unrelated frontend fixes:

- LanguageSelector mounts each time the sidebar account dropdown opens and
  unconditionally called i18n.changeLanguage() on mount, emitting a
  languageChanged event even when the language was unchanged. That handed
  every useTranslation() consumer a fresh `t` reference, re-running effects
  keyed on `t` (e.g. the plugins page system-status fetch) and surfacing as
  a page "refresh". Guard the call so it only fires on an actual change.

- Plugin logs auto-refresh control changed from a toggle Button to a
  Switch + Label; the on/off button i18n keys are replaced by a single
  static logsAutoRefresh label across all 8 locales.

web/src/i18n/locales/zh-Hans.ts

@@ -566,8 +566,7 @@ const zhHans = {
     tabLogs: '日志',
     logsLevelAll: '全部级别',
     logsRefresh: '刷新',
-    logsAutoRefreshOn: '自动刷新：开',
-    logsAutoRefreshOff: '自动刷新：关',
+    logsAutoRefresh: '自动刷新',
     logsEmpty: '暂无日志。插件通过 logger 打印的日志会显示在这里。',
     fileUpload: {
       tooLarge: '文件大小超过 10MB 限制',