fix(ai): prevent OpenAI credential error at module load time

- Moved OpenAI client initialization to a lazy getter function
- Added explicit check for NEBIUS_API_KEY in the getter
- Ensures Server Actions return structured errors instead of crashing when keys are missing

src/lib/ai-client.ts

@@ -1,6 +1,19 @@
 import { OpenAI } from 'openai';
 
-export const aiClient = new OpenAI({
-    baseURL: 'https://api.tokenfactory.nebius.com/v1/',
-    apiKey: process.env.NEBIUS_API_KEY,
-});
+/**
+ * Creates a Nebius AI client using the provided API key.
+ * This is wrapped in a function to avoid top-level initialization errors
+ * if the environment variables are not yet loaded or are missing.
+ */
+export function getNebiusClient() {
+    const apiKey = process.env.NEBIUS_API_KEY;
+
+    if (!apiKey) {
+        throw new Error('NEBIUS_API_KEY is not configured.');
+    }
+
+    return new OpenAI({
+        baseURL: 'https://api.tokenfactory.nebius.com/v1/',
+        apiKey: apiKey,
+    });
+}