feat: add authentication for Gradio app launch

app.py

@@ -1,8 +1,13 @@
+import os
+
 import gradio as gr
 from core import RAG, parse_cas_input
 
 rag = RAG()
 
+DEMO_USER = os.getenv("USERNAME", "demo")
+DEMO_PASS = os.getenv("PASSWORD", "chemical2026")
+
 EXAMPLE_INPUTS = [
     "7664-39-3",
     "7664-39-3, 128-37-0",
@@ -122,4 +127,4 @@ with gr.Blocks(
             )
 
 if __name__ == "__main__":
-    demo.launch()
+    demo.launch(auth=(DEMO_USER, DEMO_PASS))