feat: add SsePreMessageSchema and type definition for pre-messages in OpenAI interface

apps/app/src/features/openai/interfaces/knowledge-assistant/sse-schemas.ts

@@ -11,6 +11,11 @@ export const SseMessageSchema = z.object({
   })),
 });
 
+export const SsePreMessageSchema = z.object({
+  text: z.string().describe('The pre-message that should be appended to the chat window'),
+});
+
 
 // Type definitions
 export type SseMessage = z.infer<typeof SseMessageSchema>;
+export type SsePreMessage = z.infer<typeof SsePreMessageSchema>;