settings: add Data Saving Mode toggle (UI & i18n only)

Signed-off-by: Texas0295 <kimura@texas0295.top>

assets/i18n/zh-TW.json

@@ -315,6 +315,7 @@
     "settingsRealmCompactView": "緊湊領域視圖",
     "settingsMixedFeed": "混合動態",
     "settingsAutoTranslate": "自動翻譯",
+  "settingsDataSavingMode": "低數據模式",
     "settingsHideBottomNav": "隱藏底部導航",
     "settingsSoundEffects": "音效",
     "settingsAprilFoolFeatures": "愚人節功能",
@@ -825,4 +826,4 @@
     "copySecretHint": "請複製此密鑰並將其存放在安全的地方。您將無法再次看到它。",
     "expiresIn": "過期時間（秒）",
     "isOidc": "OIDC 相容"
-}
+}