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_sv.dart

@@ -817,6 +817,46 @@ class AppLocalizationsSv extends AppLocalizations {
   @override
   String get channels_sortUnread => 'Oläst';
 
+  @override
+  String get channels_createPrivateChannel => 'Skapa en privat kanal';
+
+  @override
+  String get channels_createPrivateChannelDesc =>
+      'Skyddat med en hemlig nyckel.';
+
+  @override
+  String get channels_joinPrivateChannel => 'Gå med i en Privat Kanal';
+
+  @override
+  String get channels_joinPrivateChannelDesc =>
+      'Ange en hemlig nyckel manuellt.';
+
+  @override
+  String get channels_joinPublicChannel => 'Gå med i den Offentliga Kanalen';
+
+  @override
+  String get channels_joinPublicChannelDesc =>
+      'Vem som helst kan gå med i denna kanal.';
+
+  @override
+  String get channels_joinHashtagChannel => 'Gå med i en Hashtagkanal';
+
+  @override
+  String get channels_joinHashtagChannelDesc =>
+      'Väldigt enkelt att gå med i hashtag-kanaler.';
+
+  @override
+  String get channels_scanQrCode => 'Skanna en QR-kod';
+
+  @override
+  String get channels_scanQrCodeComingSoon => 'Kommer snart';
+
+  @override
+  String get channels_enterHashtag => 'Ange hashtag';
+
+  @override
+  String get channels_hashtagHint => 't.ex. #team';
+
   @override
   String get chat_noMessages => 'Inga meddelanden ännu';