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_sl.dart

@@ -824,6 +824,45 @@ class AppLocalizationsSl extends AppLocalizations {
   @override
   String get channels_sortUnread => 'Nerešeno';
 
+  @override
+  String get channels_createPrivateChannel => 'Ustvari zasebno kanal.';
+
+  @override
+  String get channels_createPrivateChannelDesc =>
+      'Varno zaklenjeno s skrivnim ključem.';
+
+  @override
+  String get channels_joinPrivateChannel => 'Pridružite se zasebni skupini';
+
+  @override
+  String get channels_joinPrivateChannelDesc => 'Ročno vnesite zaporni ključ.';
+
+  @override
+  String get channels_joinPublicChannel => 'Pridružite se javnemu kanalu';
+
+  @override
+  String get channels_joinPublicChannelDesc =>
+      'Kdor karkoli je, lahko se pridruži tej skupini.';
+
+  @override
+  String get channels_joinHashtagChannel => 'Pridružite se Kanalu z Hashtagom';
+
+  @override
+  String get channels_joinHashtagChannelDesc =>
+      'Kdor karkoli, lahko se pridruži hashtag kanalom.';
+
+  @override
+  String get channels_scanQrCode => 'Skeniraj QR kodo';
+
+  @override
+  String get channels_scanQrCodeComingSoon => 'Prihajajoča';
+
+  @override
+  String get channels_enterHashtag => 'Vnesite hashtag';
+
+  @override
+  String get channels_hashtagHint => 'npr. #ekipa';
+
   @override
   String get chat_noMessages => 'Še ni sporočil.';