Path.read_text() uses the system locale by default. On Windows CN/JP/KR
locales (GBK/CP932/CP949), reading a UTF-8 .env raises UnicodeDecodeError
as soon as it contains any non-ASCII byte (e.g. an em dash).
Pin encoding="utf-8" on every .env read in hermes_cli to match how the
rest of the codebase (load_dotenv at doctor.py:26) already decodes it.
Adds a regression test that monkeypatches Path.read_text to simulate a
GBK locale and asserts 'hermes doctor' no longer raises.
Refs #18637
c5e3a6fb5b