docs: clarify oauth vs api key and add setup steps

scripts/manage_secrets.py

@@ -109,6 +109,12 @@ def main():
             create_secret(secret_id)
         
         # Prompt for value
+        if secret_id == "haumdaucher-oauth-client-id":
+            print(f"   ℹ️  Go to GCP Console > Credentials > OAuth 2.0 Client IDs")
+            print(f"      Copy the 'Client ID' (ends in .apps.googleusercontent.com)")
+        elif secret_id == "haumdaucher-oauth-client-secret":
+             print(f"   ℹ️  Copy the 'Client Secret' (shorter string, hidden in console)")
+
         print(f"   Enter value for {description} (Input hidden): ")
         # Use getpass logic via manual read to support all shells or just input() but masked? 
         # getpass in python is better.