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/ja-JP.ts

@@ -598,8 +598,7 @@ const jaJP = {
     tabLogs: 'ログ',
     logsLevelAll: 'すべてのレベル',
     logsRefresh: '更新',
-    logsAutoRefreshOn: '自動更新：オン',
-    logsAutoRefreshOff: '自動更新：オフ',
+    logsAutoRefresh: '自動更新',
     logsEmpty:
       'ログはまだありません。プラグインが logger で出力したログがここに表示されます。',
     fileUpload: {