Optional dev boot: documented env to skip or soften facial gate

[rosspeili]

Problem

docs/BOOT_AND_SECURITY.md states missing face in enrollment, camera failure, emotion deny, and timeouts can sys.exit(). docs/TROUBLESHOOTING.md suggests stubbing facial_recognition_auth in a fork—no first-party switch.

Goal

Supported development-only path (explicit env var, e.g. OPSIIE_SKIP_FACIAL_AUTH=1—exact name TBD) that:

• bypasses or uses a stub user from kun.py demo profile;
• prints a loud warning that production use is discouraged.

Acceptance criteria

• Documented in .env.example and docs/BOOT_AND_SECURITY.md.
• Never default on; impossible to enable accidentally via missing env (must be explicit 1/true).
• SECURITY.md / threat notes updated if behavior changes assumptions.