feat(bench): perp-exit-custody bench 123

[Flotapponnier]

Summary

• Adds bench 123: perp-exit-custody — worst-case hours for a user to withdraw without operator/validator cooperation, across 7 perp DEX venues
• Static scanner data for 4 EVM venues (gains, gmx-v2, ostium, vertex) in harnesses/permissions-scan/out/ with confidence tiers per field
• Non-EVM venue data for Hyperliquid, Lighter, Aster from L2Beat + official docs
• Live Prometheus metrics declared: perp_exit_settlement_age_hours{venue=ostium}, perp_exit_epoch_number{venue=gains}, perp_exit_bridge_balance_usd{venue=hyperliquid}

Key findings

• Lighter: only venue with bounded worst-case exit — 336h (14-day Desert Mode, self-provable ZK proof)
• Ostium: only EVM venue with permissionless fallback — tryNewSettlement() is public, 720h worst-case (3x 30-day intervals)
• gains/GMX/Hyperliquid/Aster: no permissionless exit path (oracle/keeper/validator required)
• Vertex: implementation contracts unverified on Arbiscan; exit architecture opaque
• GMX finding: 2 of 4 TIMELOCK_ADMIN holders are plain EOAs (no multisig)

Test plan

• Validate bench YAML passes SpecSchema (npx tsx validation confirmed locally: VALID)
• Staging preview renders bench 123 page at /bench/perp-exit-custody
• Live metrics require harness deployment (deferred; bench renders static data until harness is live)

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