test(erc4626spec): add ERC-4626 spec compliance tests for OffchainAssetReceiptVault

[thedavidmeister]

Summary

Adds OffchainAssetReceiptVault.erc4626spec.t.sol with 9 fuzz tests covering the ERC-4626 spec invariants flagged in #303.

max* MUST NOT revert (ERC-4626 §4.8):

• testMaxWithdrawAnyIdDoesNotRevert — fuzz all (owner, id) pairs including id == 0
• testMaxWithdrawZeroIdDoesNotRevert — explicit id == 0 pin (the concrete bug from Add ERC4626 spec compliance test suite #303)
• testMaxRedeemAnyIdDoesNotRevert — fuzz all (owner, id) pairs
• testMaxDepositAnyOwnerDoesNotRevert — pure, always returns type(uint256).max
• testMaxMintAnyOwnerDoesNotRevert — pure, always returns type(uint256).max

Inverse relationship (ERC-4626 §4.9):

• testConvertToInverses — convertToAssets(convertToShares(x)) == x for all x > 0 and all id > 0

Immutability (ERC-4626 §4.1):

• testAssetImmutableAfterOperations — asset() unchanged before/after deposit+withdraw

preview* consistency (ERC-4626 §4.3–4.6):

• testPreviewDepositMatchesDeposit — previewDeposit(assets, 0) matches shares credited by deposit
• testPreviewRedeemMatchesRedeem — previewRedeem(shares, 1) matches assets returned by redeem

For this vault _shareRatioUserAgnostic always returns 1e18, so the 1:1 invariant holds across all functions. The id == 0 divide-by-zero guard (added to ReceiptVault.maxWithdraw) is correct and these tests pin it against future subclass overrides.

Note: totalAssets consistency and decimals/rounding are already covered by the existing OffchainAssetReceiptVault.totalAssets.t.sol and OffchainAssetReceiptVault.convertToAssets.t.sol/convertToShares.t.sol.

Closes #303

Co-Authored-By: Claude noreply@anthropic.com

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 607d362c-a6fd-48e6-980f-55af2b0efdbf

📥 Commits

Reviewing files that changed from the base of the PR and between 8f68b12 and 3f4f392.

📒 Files selected for processing (2)

• .pre-commit-config.yaml
• test/src/concrete/vault/OffchainAssetReceiptVault.erc4626spec.t.sol

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-06-21-issue-303-erc4626-spec-compliance

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