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_pl.dart

@@ -828,6 +828,46 @@ class AppLocalizationsPl extends AppLocalizations {
   @override
   String get channels_sortUnread => 'Niezgłoszone';
 
+  @override
+  String get channels_createPrivateChannel => 'Utwórz Prywatny Kanał';
+
+  @override
+  String get channels_createPrivateChannelDesc =>
+      'Zabezpieczone kluczem szyfrowym.';
+
+  @override
+  String get channels_joinPrivateChannel => 'Dołącz do Prywatnego Kanału';
+
+  @override
+  String get channels_joinPrivateChannelDesc => 'Ręcznie wprowadź klucz tajny.';
+
+  @override
+  String get channels_joinPublicChannel => 'Dołącz do kanału publicznego.';
+
+  @override
+  String get channels_joinPublicChannelDesc =>
+      'Każdy może dołączyć do tego kanału.';
+
+  @override
+  String get channels_joinHashtagChannel =>
+      'Dołącz do kanału oznaczanego hashtagiem';
+
+  @override
+  String get channels_joinHashtagChannelDesc =>
+      'Każdy może dołączyć do kanałów z hashtagami.';
+
+  @override
+  String get channels_scanQrCode => 'Skanuj kod QR';
+
+  @override
+  String get channels_scanQrCodeComingSoon => 'Wkrótce';
+
+  @override
+  String get channels_enterHashtag => 'Wprowadź hashtag';
+
+  @override
+  String get channels_hashtagHint => 'np. #zespół';
+
   @override
   String get chat_noMessages => 'Brak jeszcze wiadomości';