Add support for private and hashtag channels in localization and channel management

- Updated Polish, Portuguese, Slovak, Slovenian, Swedish, and Chinese localization files to include new strings for creating and joining private channels, as well as joining hashtag channels.
- Enhanced the channel management UI to allow users to create and join private channels, join public channels, and join channels via hashtags.
- Implemented PSK derivation from hashtags using SHA256 in the Channel model.
- Improved the translation script to handle missing keys and translate all locales efficiently.

lib/l10n/app_localizations_de.dart

@@ -828,6 +828,48 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get channels_sortUnread => 'Unlescht';
 
+  @override
+  String get channels_createPrivateChannel => 'Erstelle einen privaten Kanal';
+
+  @override
+  String get channels_createPrivateChannelDesc =>
+      'Verschlüsselt mit einem geheimen Schlüssel.';
+
+  @override
+  String get channels_joinPrivateChannel =>
+      'Treten Sie einem privaten Kanal bei';
+
+  @override
+  String get channels_joinPrivateChannelDesc =>
+      'Manuelle Eingabe eines geheimen Schlüssels.';
+
+  @override
+  String get channels_joinPublicChannel => 'Tritt dem öffentlichen Kanal bei';
+
+  @override
+  String get channels_joinPublicChannelDesc =>
+      'Jeder kann diesem Kanal beitreten.';
+
+  @override
+  String get channels_joinHashtagChannel =>
+      'Treten Sie einem Hashtag-Kanal bei';
+
+  @override
+  String get channels_joinHashtagChannelDesc =>
+      'Jeder kann sich bei Hashtag-Kanälen beteiligen.';
+
+  @override
+  String get channels_scanQrCode => 'Scannen Sie einen QR-Code';
+
+  @override
+  String get channels_scanQrCodeComingSoon => 'Bald verfügbar';
+
+  @override
+  String get channels_enterHashtag => 'Gib Hashtag ein';
+
+  @override
+  String get channels_hashtagHint => 'z.B. #team';
+
   @override
   String get chat_noMessages => 'Noch keine Nachrichten.';