debug: print GROQ key prefix in logs

api.py

@@ -1,3 +1,4 @@
+import os
 from fastapi import FastAPI
 from fastapi.staticfiles import StaticFiles
 from fastapi.responses import HTMLResponse
@@ -6,6 +7,9 @@ from src.rag import answer
 
 app = FastAPI(title="Vietnamese RAG API")
 
+groq_key = os.environ.get("GROQ_API_KEY", "NOT_SET")
+print(f"DEBUG GROQ_API_KEY: '{groq_key[:8]}...{groq_key[-4:]}' len={len(groq_key)}")
+
 
 class QueryRequest(BaseModel):
     question: str