sync: update from private huggingface space

.env.example

@@ -105,6 +105,9 @@ LLM_API_KEY=your_api_key_here
 #
 # NVIDIA (NVIDIA_API_KEY):
 #   - nvidia/nemotron-3-super-120b-a12b
+# Optional: NVIDIA key rotation pool
+# Comma-separated keys, rotated per request
+# NVIDIA_API_KEYS=key1,key2,key3
 #
 # Groq (GROQ_API_KEY):
 #   - groq/mixtral-8x7b-32768