Support claiming legacy redeem requests

[naddison36]

Summary

• Move reservedWithdrawLiquidity to a new storage slot and preserve the legacy packed withdrawal queue slot.
• Add one-step upgrade compatibility for legacy LP withdrawal requests with shares == 0.
• Convert LP-path revert strings to custom errors to keep ARM implementations under EIP-170.
• Update migration, unit, fork, and upgrade guard tests for pending legacy withdrawal queues.

Details

Legacy asset-denominated LP withdrawal requests can now be claimed after the upgrade instead of requiring the old queue to be fully drained before upgradeToAndCall.

New share-escrowed requests continue to use the new share-based queue accounting, while legacy requests use the preserved _deprecatedWithdrawsQueued/_deprecatedWithdrawsClaimed counters.

Swap-facing revert strings are intentionally unchanged for compatibility.

Testing

• forge test --match-path 'test/unit/OriginARM/{Deposit,RequestRedeem,ClaimRedeem,MigrateLegacyWithdrawQueue}.sol' -vv
• forge test --match-path 'test/fork/LidoARM/{Deposit,ClaimRedeem}.t.sol' -vv
• forge test --match-path 'test/deploy/*UpgradeGuards.t.sol' -vv
• forge build --sizes | rg '(^|\| )(LidoARM|OriginARM|EthenaARM|EtherFiARM|ReentrantGuardHarnessARM) '
• git diff --check

Contract Sizes

EthenaARM   23,699 B   margin +877 B
EtherFiARM  24,469 B   margin +107 B
LidoARM     24,430 B   margin +146 B
OriginARM   23,680 B   margin +896 B

[clement-ux]

Some comments, but lgtm 👍