T3→Vox CI/TOESTUB enforcement v5.5 closure

Closure note for milestone v5.5 (Phases 307–312), the follow-up to the v5.4 CI and TOESTUB enforcement work. It lists what the milestone added: contributor trust gates, the privileged preview trust-split policy, intake of live transfer-budget samples, new test, host and schema detectors, the DOM test-environment ban, and content-hash fingerprinting for the GUI sidecar. Per-gem status lives in the enforcement scorecard contract, and items marked Partial there are deliberate, documented residuals rather than silent skips.

Milestone v5.5 (Phases 307–312) deepens v5.4 CI/TOESTUB enforcement with contributor trust, privileged-preview policy, live transfer-budget sample intake, test/host/schema detectors, DOM-env ban, and sidecar content-hash fingerprinting.

See contracts/reports/t3-vox-ci-enforcement-scorecard.v1.json for per-gem status. Residuals called Partial are intentional — not silent skips.