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_en.arb

@@ -361,6 +361,18 @@
   "channels_sortAZ": "A-Z",
   "channels_sortLatestMessages": "Latest messages",
   "channels_sortUnread": "Unread",
+  "channels_createPrivateChannel": "Create a Private Channel",
+  "channels_createPrivateChannelDesc": "Secured with a secret key.",
+  "channels_joinPrivateChannel": "Join a Private Channel",
+  "channels_joinPrivateChannelDesc": "Manually enter a secret key.",
+  "channels_joinPublicChannel": "Join the Public Channel",
+  "channels_joinPublicChannelDesc": "Anyone can join this channel.",
+  "channels_joinHashtagChannel": "Join a Hashtag Channel",
+  "channels_joinHashtagChannelDesc": "Anyone can join hashtag channels.",
+  "channels_scanQrCode": "Scan a QR Code",
+  "channels_scanQrCodeComingSoon": "Coming soon",
+  "channels_enterHashtag": "Enter hashtag",
+  "channels_hashtagHint": "e.g. #team",
 
   "chat_noMessages": "No messages yet",
   "chat_sendMessageToStart": "Send a message to get started",