Pin Unlink case to dynamic event source support

[Th0rgal]

Summary

• bump the benchmark Verity pin to lfglabs-dev/verity@3b7e69b
• record Verity #1870 and #1871 in the Unlink case notes

Verification

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

Notes

The Unlink case still carries dynamic_array_event_payloads as unsupported because the executable emit surface remains homogeneous (List Uint256) and cannot yet typecheck source-level mixed scalar/array event arguments.

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Note

Low Risk
Low risk: this only updates the pinned verity dependency and corresponding case metadata/notes, with no changes to benchmark/proof logic itself.

Overview
Pins the benchmark’s verity dependency to commit 3b7e69b (via lakefile.lean and lake-manifest.json) to pick up newer translation support.

Updates the UnlinkXyz pool case metadata to match the new Verity pin and records the relevant upstream Verity PRs (#1870 memory-array helper lowering and #1871 dynamic-array event sources) in the case notes.

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