Rewrite Python code samples to read credentials from environment
via load_credentials_from_env() helper rather than literal kwargs.
Avoids triggering pre-commit secrets scanners on 'password=' pattern
in training data while improving security guidance shown to readers.
Replace literal 'apipass'/'admin' placeholder credentials with
explicit <USER>/<PASSWORD> placeholders. Prevents false-positive
secrets scan detection in Magatama pre-commit hooks.
No real credentials were ever present — these are training
data code examples showing API connection patterns.
