feat: integrate link handling in chat screen with linkify support

- Added flutter_linkify package to auto-detect and linkify URLs in chat messages.
- Implemented LinkHandler class to manage link tap confirmations and URL launching.
- Updated chat_screen.dart to use Linkify for displaying message text with links.
- Registered url_launcher plugin for handling URL launches across platforms.
- Updated pubspec.yaml and pubspec.lock to include new dependencies.
- Cleaned up untranslated.json by removing unused translations.

android/app/src/main/AndroidManifest.xml

@@ -67,5 +67,14 @@
             <action android:name="android.intent.action.PROCESS_TEXT"/>
             <data android:mimeType="text/plain"/>
         </intent>
+        <!-- URL launcher intents for opening links -->
+        <intent>
+            <action android:name="android.intent.action.VIEW"/>
+            <data android:scheme="http"/>
+        </intent>
+        <intent>
+            <action android:name="android.intent.action.VIEW"/>
+            <data android:scheme="https"/>
+        </intent>
     </queries>
 </manifest>