feat: implement create-chat-conversation function with OpenAI integration and Supabase support

- Added CORS handling for the create-chat-conversation function.
- Implemented health check endpoint for the function.
- Created endpoints for managing conversations and messages with OpenAI.
- Added error handling and response formatting for better API usability.
- Introduced utility functions for environment variable management and Supabase client creation.
- Enhanced schema handling for structured responses from OpenAI.
- Implemented conversation archiving and retrieval logic.

supabase/functions/create-chat-conversation/lib/openai.ts

@@ -0,0 +1,9 @@
+import OpenAI from "npm:openai@6.16.0";
+import { mustGetEnv } from "./env.ts";
+
+export function getOpenAI() {
+  // OpenAI lib toma OPENAI_API_KEY de env automáticamente,
+  // pero lo validamos para fallar rápido:
+  mustGetEnv("OPENAI_API_KEY");
+  return new OpenAI();
+}