flow skill v0.28.1 — Attestation harden

Harden package (post independent parallel review)

1. Mint blob-exec — materialize committed owner/command/oracle blobs at --revision; disk must match (no dirty worktree pass)
2. Live currentness — exact HEAD tip + recomputed owner/oracle fingerprints
3. Cleanliness — mint/consume/auto; allow .flow/, flow/.lock*, status/Evidence-only card dirt
4. Empty range — reject card semantic when base == revision
5. Supervisor — real setsid PGID kill + capability probe
6. coverage_gaps — auto expects v0.28 fail-closed without git/receipts

Skill 0.28.1 · npm 0.5.1