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.

lib/core/auth/api_auth_interceptor.dart

@@ -112,17 +112,14 @@ class ApiAuthInterceptor extends Interceptor {
     // Add custom headers from server config (with safety checks)
     if (customHeaders.isNotEmpty) {
       customHeaders.forEach((key, value) {
-        // Don't override critical headers that we manage
         final lowerKey = key.toLowerCase();
-        if (lowerKey != 'authorization' &&
-            lowerKey != 'content-type' &&
-            lowerKey != 'accept') {
-          options.headers[key] = value;
-        } else {
+        if (lowerKey == 'authorization') {
           DebugLogger.warning(
             'Skipping reserved header override attempt: $key',
           );
+          return;
         }
+        options.headers[key] = value;
       });
     }