refactor: rename substance header class to section title for consistency

apps/app/src/features/openai/client/components/AiAssistant/Sidebar/AiAssistantList.module.scss

@@ -10,7 +10,7 @@
 }
 
 .ai-assistant-list :global {
-  .grw-ai-assistant-substance-header {
+  .grw-assistant-section-title {
     font-size: 14px;
   }
 }

apps/app/src/features/openai/client/components/AiAssistant/Sidebar/AiAssistantList.tsx

@@ -308,7 +308,7 @@ export const AiAssistantList: React.FC<AiAssistantListProps> = ({
         aria-expanded="false"
         onClick={toggleCollapse}
       >
-        <h3 className="fw-bold grw-ai-assistant-substance-header mb-0 me-1">
+        <h3 className="fw-bold grw-assistant-section-title mb-0 me-1">
           {t(isTeamAssistant ? 'ai_assistant_list.team_assistants' : 'ai_assistant_list.my_assistants')}
         </h3>
         <span