refactor: migrate to flutter_math_fork and markdown_widget for enhanced markdown capabilities

- Replaced flutter_markdown_plus with flutter_math_fork to improve mathematical rendering within markdown content.
- Integrated markdown_widget for better markdown processing and rendering, enhancing overall user experience.
- Updated the markdown configuration to utilize the new packages, ensuring maintainability and adaptability of markdown features.
- Refactored the streaming markdown widget to accommodate the new markdown processing logic, improving code clarity and performance.

pubspec.yaml

@@ -30,7 +30,6 @@ dependencies:
   shared_preferences: ^2.3.2
   
   # UI Components - GPT Markdown  
-  flutter_markdown_plus: ^1.0.3
   cached_network_image: ^3.3.1
   flutter_highlight: ^0.7.0
   webview_flutter: ^4.7.0
@@ -66,6 +65,9 @@ dependencies:
   share_plus: ^12.0.0
   share_handler: ^0.0.19
   riverpod_annotation: ^3.0.0
+  markdown_widget: ^2.3.2+8
+  flutter_math_fork: ^0.7.4
+  markdown: ^7.3.0
   
   # Clipboard functionality is available through flutter/services (part of Flutter SDK)