ci(release): recompute evidence digest at tag time; adopt shared-CI 0.8.1

[rldyourmnd]

Why

Independent verification of two confirmed findings against ground truth:

• Tag-time evidence gate was shape-only. The public Verify release-evidence bundle step checked the digest format but never recomputed it from the tagged tree, and enforced no freshness/completeness. The strong content-recompute lived only in the private harness, which the public tag-push path never runs — so the release control point could not prove the bundle bound to the released content.
• Shared-CI drift past a permission fix. nddev-ci-workflows advanced 0.7.0 → 0.8.1; feat(release): publish the minimal runtime bundle as a second asset #13 (0a059bc) added the artifact-metadata: write scope the attest jobs require (actions/attest v4.1.1). This repo was still pinned to 0.7.0/eda8ff7, and the publish caller did not grant that scope (reusable-workflow permissions intersect with the caller ceiling).

What

• Harden Verify release-evidence bundle: recompute setup_digest from git ls-files -s (excluding the bundle itself — identical to scripts/evidence.compute_setup_digest) and fail closed on mismatch; enforce freshness (generated <= now < expires) and structural completeness (vendor, platforms, non-empty checks).
• Re-pin all 7 shared callers 0.7.0 → 0.8.1 (eda8ff7 → 8b8e3ea).
• Grant artifact-metadata: write on the publish job.
• Regenerate build/release-evidence.json so its digest matches the new content.

Verification

• actionlint clean on all changed workflows.
• Extracted tag-time verifier run against the checkout → recompute matches compute_setup_digest (sha256:1868c895…); emit_evidence.py --check valid.
• No workflow_call input changed 0.7.0↔0.8.1 (interface-compatible; only the additive permission + a Syft bump + a SLSA label edit).

Harness pin advance + contract-test updates follow in nddev-harnesses.