feat: add view function for mint precompile allowlist

[johnletey]

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Refactoring

Related Issues

Fixes #(issue)

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Testing

Additional Notes

[gemini-code-assist]

Summary of Changes

Hello @johnletey, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new read-only function to the mint precompile, allowing users to query the allowlist status of any given address. This enhancement improves transparency by providing a direct way to verify whether an account is permitted to perform minting operations, without altering the blockchain state.

Highlights

• New View Function: A new allowlist view function has been added to the INativeToken interface, enabling external callers to check if a specific address is on the mint precompile's allowlist.
• Precompile Implementation: The MintPrecompile now includes the implementation for the allowlist function, which queries the allowlist status and returns a boolean value.
• Documentation Updates: The INativeToken interface definition has been updated in both the README.md and the ADR-0002-native-minting-precompile.md to reflect the addition of the new allowlist view function.

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[gemini-code-assist]

Code Review

This pull request introduces a new view function, allowlist(address), to the mint precompile. This allows users to check if an account is on the minting allowlist. The changes include updating the Solidity interface in the documentation and implementing the corresponding logic in the Rust precompile. My review identifies a key issue where the new view function can potentially modify state, which violates EVM conventions. I've provided a detailed comment and a code suggestion to address this. The rest of the changes, including documentation, are correct and consistent.

[gemini-code-assist]

The allowlist function is declared as view in the Solidity interface, which implies it must not modify blockchain state. The current implementation calls Self::is_allowlisted, which in turn calls Self::ensure_account_created. This can cause a state modification by creating the precompile's account if it doesn't already exist. This side effect violates the read-only guarantee of a view function and can lead to inconsistent behavior across different EVM clients and tools.

To fix this, the read-only logic from is_allowlisted should be inlined here, avoiding the state-mutating call. For consistent logging, you should also duplicate the tracing::debug! call from is_allowlisted.

            INativeToken::INativeTokenCalls::allowlist(call) => {
                // This is a view function; avoid state modifications from `is_allowlisted`.
                let key = Self::allowlist_key(call.account);
                let value = internals
                    .sload(MINT_PRECOMPILE_ADDR, key)
                    .map_err(Self::map_internals_error)?;
                let is_allowed = !value.is_zero();
                let result = is_allowed.abi_encode();
                Ok(PrecompileOutput::new(0, result.into()))
            }