- _prompt() clamps non-positive tuning values to default with operator warning
(HIGH from AUDIT_SEC_989: prevents garbage display when vars file has
masscan_rate: -100 or nuclei_concurrency: 0)
- Remove empty 'if scan_mode in (...): pass' placeholder left from refactor
(P3 from AUDIT_CODE_989)
- Add AUDIT_CODE/SEC/ENV_989.md and FIXES_989.md with skip justifications
(path traversal not applicable to single-operator threat model;
Tor wording already adequate; estimate disclosure interactive-only)