Implement EIP-2565 ModExp precompile support in AuRa tests

[richardgreg]

This commit implements the TODO for ModExp precompile EIP-2565 support in ChainSpecLoaderTest.

Changes

• Added test/Specs/posdao.json with the required chain spec format
• Created a new test method to verify EIP-2565 transition parameter is properly set
• Added proper documentation to explain the ModExp precompile gas cost changes

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• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

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Documentation

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[Copilot]

Pull Request Overview

This PR adds tests to verify the EIP-2565 ModExp precompile support in AuRa by ensuring that the chain spec parameters and call depth limits are correctly handled under various EVM operations.

• Adds new tests in CallDepthLimitTests.cs to cover recursive CALL, CREATE, and DELEGATECALL operations failing at maximum depth (1024).
• Updates ChainSpecLoaderTest.cs to verify that the Eip2565Transition parameter is explicitly set in the chain specification.

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Nethermind/Nethermind.Evm.Test/CallDepthLimitTests.cs	Introduces tests for recursive calls, create, and delegatecall failures at max depth to ensure proper handling of gas limits and depth restrictions.
src/Nethermind/Nethermind.AuRa.Test/ChainSpecLoaderTest.cs	Adds a test that assigns and verifies the Eip2565Transition parameter in the chain spec.

Files not reviewed (1)

• src/Nethermind/Nethermind.AuRa.Test/Specs/posdao.json: Language not supported

Comments suppressed due to low confidence (3)

src/Nethermind/Nethermind.Evm.Test/CallDepthLimitTests.cs:158

• [nitpick] Consider defining a constant (e.g. MAX_CALL_DEPTH) instead of using the magic number 1024 directly for clarity and consistency.

Assert.That(depth, Is.EqualTo((UInt256)1024), "Call should fail at depth 1024");

src/Nethermind/Nethermind.Evm.Test/CallDepthLimitTests.cs:265

• [nitpick] Consider defining a constant (e.g. MAX_CALL_DEPTH) to replace the magic number 1024, which will improve code clarity and ease updates if the depth limit changes.

Assert.That(depth, Is.EqualTo((UInt256)1024), "CREATE should fail at depth 1024");

src/Nethermind/Nethermind.Evm.Test/CallDepthLimitTests.cs:363

• [nitpick] Consider replacing the hard-coded value 1024 with a defined constant (e.g. MAX_CALL_DEPTH) to enhance the maintainability of the test cases.

Assert.That(depth, Is.EqualTo((UInt256)1024), "DELEGATECALL should fail at depth 1024");