fix(landing): use a realistic UUID for profile_id in API example

Profile IDs are str(uuid.uuid4()), not slugs (see backend/services/profiles.py:175).

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

landing/src/components/ApiSection.tsx

@@ -29,7 +29,7 @@ const CURL_SNIPPET = `curl -X POST http://127.0.0.1:17493/generate \\
   -H "Content-Type: application/json" \\
   -d '{
     "text": "Welcome to the game, player one.",
-    "profile_id": "morgan-freeman",
+    "profile_id": "b3f1c2d4-5e6f-4a7b-8c9d-0e1f2a3b4c5d",
     "engine": "qwen_custom_voice",
     "instruct": "warm, slow, cinematic"
   }' \\