feat(privacy): add personalized ads toggle in settings

- Add PrivacySettings schema with can_sell field (default: false)
- Move privacy toggle to GeneralSettingsScreen with clear labeling
- Update l10n for zh/en/zh_hant with user-friendly copy
- Clean up redundant PrivacyNotificationSettingsScreen
- Update profile-protocol.md to reflect new privacy schema
- Fix basedpyright warnings in user.py

apps/lib/l10n/app_localizations.dart

@@ -2300,6 +2300,30 @@ abstract class AppLocalizations {
   /// In zh, this message translates to:
   /// **'请输入有效的6位邀请码'**
   String get settingsInviteInvalidCode;
+
+  /// No description provided for @settingsDoNotSellTitle.
+  ///
+  /// In zh, this message translates to:
+  /// **'个性化广告推荐'**
+  String get settingsDoNotSellTitle;
+
+  /// No description provided for @settingsDoNotSellDescription.
+  ///
+  /// In zh, this message translates to:
+  /// **'关闭后，我们不会将您的个人信息用于广告推荐'**
+  String get settingsDoNotSellDescription;
+
+  /// No description provided for @settingsDoNotSellEnabled.
+  ///
+  /// In zh, this message translates to:
+  /// **'已关闭'**
+  String get settingsDoNotSellEnabled;
+
+  /// No description provided for @settingsDoNotSellDisabled.
+  ///
+  /// In zh, this message translates to:
+  /// **'已开启'**
+  String get settingsDoNotSellDisabled;
 }
 
 class _AppLocalizationsDelegate