#68 FTX-68: Real E2E harness

tests/e2e/ marker e2e, zero mocks: futex_api + futex_worker subprocesses against futex_test; real auth :4000; real mail-api -> postfix -> /var/mail/{frank,sara} read via sudo cat with offset snapshots + uuid correlation; webhook receiver :8925 with HMAC verify; full flow: policy -> decision -> real mail -> review link -> CSRF approve -> approved -> envelope + terminal webhook + audit. Variants: reject/idempotency/expiry/one-click/OTP/delegation/MCP parity/mail-outage. Phase 9.