feat(assurance): add public v60 Seed stutter assurance

[bros-labs-ai]

Summary

Add a non-normative public-v60 Seed stutter assurance perimeter for the ASET Worker Extension.

The assurance composes existing mechanically established evidence over the exact same frozen SeedResolution subject:

• Worker -> Seed refinement evidence: 19/19
• public ASET v60 recognition-boundary evidence: 2257/2257
• exact shared SeedResolution subject binding: PASS

Claim boundary

This does not modify Worker normative semantics.

It does not claim a new mechanically composed Worker-to-v60 theorem. The Worker continues to add no Seed recognition state, does not create terminal recognition, and does not grant Seed effect permission.

The assurance verifies that the existing Worker -> Seed stutter/refinement evidence and public v60 evidence protect the same frozen Seed subject.

Validation

• Worker local gate: PASS
• canonical projection: PASS
• canon package: 34/34 PASS
• Worker conformance: 12/12 PASS
• finite model: PASS
• materialized TLAPS safety: MECHANICALLY_PROVED
• materialized canon-to-TLA: MECHANICALLY_PROVED
• materialized Seed refinement: MECHANICALLY_PROVED
• Seed refinement evidence: 19/19
• public v60 evidence: 2257/2257
• Seed stutter assurance: PASS
• pytest: PASS
• new assurance Python surface Ruff format/check: PASS