feat: add message translation support

- Introduced translation functionality in chat screen, allowing users to translate messages before sending.
- Added MessageTranslationButton to the input bar for enabling/disabling translation.
- Implemented translation service to handle incoming and outgoing text translations using llama models.
- Enhanced message storage to include original and translated text, language codes, and translation status.
- Created UI components for displaying translated messages and managing translation options.
- Added translation model management, including downloading and storing models locally.
- Updated app settings to manage translation preferences and model selections.

lib/models/channel_message.dart

@@ -2,6 +2,7 @@ import 'dart:typed_data';
 import '../connector/meshcore_protocol.dart';
 import '../helpers/reaction_helper.dart';
 import '../helpers/smaz.dart';
+import 'translation_support.dart';
 import '../utils/app_logger.dart';
 
 enum ChannelMessageStatus { pending, sent, failed }
@@ -24,9 +25,16 @@ class Repeat {
 }
 
 class ChannelMessage {
+  static const Object _unset = Object();
+
   final Uint8List? senderKey;
   final String senderName;
   final String text;
+  final String? originalText;
+  final String? translatedText;
+  final String? translatedLanguageCode;
+  final MessageTranslationStatus translationStatus;
+  final String? translationModelId;
   final DateTime timestamp;
   final bool isOutgoing;
   final ChannelMessageStatus status;
@@ -47,6 +55,11 @@ class ChannelMessage {
     this.senderKey,
     required this.senderName,
     required this.text,
+    this.originalText,
+    this.translatedText,
+    this.translatedLanguageCode,
+    this.translationStatus = MessageTranslationStatus.none,
+    this.translationModelId,
     required this.timestamp,
     required this.isOutgoing,
     this.status = ChannelMessageStatus.pending,
@@ -86,12 +99,30 @@ class ChannelMessage {
     String? replyToMessageId,
     String? replyToSenderName,
     String? replyToText,
+    Object? originalText = _unset,
+    Object? translatedText = _unset,
+    Object? translatedLanguageCode = _unset,
+    MessageTranslationStatus? translationStatus,
+    Object? translationModelId = _unset,
     Map<String, int>? reactions,
   }) {
     return ChannelMessage(
       senderKey: senderKey,
       senderName: senderName,
       text: text,
+      originalText: originalText == _unset
+          ? this.originalText
+          : originalText as String?,
+      translatedText: translatedText == _unset
+          ? this.translatedText
+          : translatedText as String?,
+      translatedLanguageCode: translatedLanguageCode == _unset
+          ? this.translatedLanguageCode
+          : translatedLanguageCode as String?,
+      translationStatus: translationStatus ?? this.translationStatus,
+      translationModelId: translationModelId == _unset
+          ? this.translationModelId
+          : translationModelId as String?,
       timestamp: timestamp,
       isOutgoing: isOutgoing,
       status: status ?? this.status,
@@ -191,12 +222,18 @@ class ChannelMessage {
   static ChannelMessage outgoing(
     String text,
     String senderName,
-    int channelIndex,
-  ) {
+    int channelIndex, {
+    String? originalText,
+    String? translatedLanguageCode,
+    String? translationModelId,
+  }) {
     return ChannelMessage(
       senderKey: null,
       senderName: senderName,
       text: text,
+      originalText: originalText,
+      translatedLanguageCode: translatedLanguageCode,
+      translationModelId: translationModelId,
       timestamp: DateTime.now(),
       isOutgoing: true,
       status: ChannelMessageStatus.pending,