Reduce `mail.py` / `kun.py` import-time coupling for credentials

[rosspeili]

Problem

OPSIIE_0_3_80_XP.py does from mail import send_mail, inbox_interaction, EMAIL, PASSWORD—binding mail module import to kun profile materialization. Makes testing and partial stacks harder.

Goal

Lazy-read mail credentials inside functions that send/receive, or a small get_mail_config() that reads from kun at call time, with same runtime behavior.

Acceptance criteria

• No credential regression; SMTP/IMAP still work for demo profile.
• Easier to mock in tests (ties to CI issue if desired).