Pin Verity macro memory array bind support

[Th0rgal]

Summary

• pin verity-benchmark to Verity 5781a22489c721670f33bc1a74563cacd7d9232b
• update UnlinkPool case metadata to match the pinned Verity revision
• refresh lake-manifest.json

Verification

• lake update verity
• lake build Benchmark.Cases.UnlinkXyz.Pool.Compile
• git diff --check

Note: the compile target still reports the existing unused PERMIT2 warning.

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Note

Medium Risk
Bumps the pinned verity git revision, which can subtly change translation/verification behavior and reproducibility even though no local logic is modified.

Overview
Pins the verity dependency to commit 5781a22489c7... by updating lakefile.lean and refreshing lake-manifest.json to match.

Updates the cases/unlink_xyz/pool/case.yaml metadata (verity_version) to stay consistent with the new pinned Verity revision.

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