fix: 显示下发智能体的云端图标

shared/coding-teacher.ts

@@ -16,6 +16,7 @@ export interface TeacherDefinition {
   name: string;
   description: string;
   avatar_id: string;
+  icon_url?: string | null;
   welcome_message: string;
   suggested_questions: string[];
   system_prompt: string;