fix: auth checking

app.py

@@ -12,10 +12,8 @@ from planning_ai.preprocessing.azure_doc import azure_process_pdfs
 from planning_ai.preprocessing.gcpt3 import main as preprocess_main
 
 # Load authentication secrets
-if Path(".streamlit/secrets.toml").exists():
-    auth = st.secrets.to_dict()
-else:
-    auth = {}
+auth = st.secrets.to_dict()
+if "credentials" not in auth:
     auth["credentials"] = {
         "usernames": {
             "admin": {