Add support for the Filecoin.EthGetStorageAt V2

[sudo-shashank]

Summary of changes

Changes introduced in this pull request:

• Impl Filecoin.EthGetStorageAt V2 and added test.

Reference issue to close (if applicable)

Closes #6301

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

Outside contributions

• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• New Features

  • Implemented Filecoin.EthGetStorageAt for API v2, providing storage value retrieval with extended block parameter support.

• Tests

  • Added test cases for the V2 storage endpoint covering current, safe, and finalized block references.

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[coderabbitai]

Walkthrough

This PR implements the Filecoin.EthGetStorageAt RPC method for API v2 by introducing a new EthGetStorageAtV2 variant that accepts extended block parameters. Core storage retrieval logic is extracted into a shared helper function, which both the original and new implementations delegate to. Tests and snapshots are added for the new endpoint.

Changes

Cohort / File(s)	Summary
Core RPC Implementation src/rpc/methods/eth.rs	Introduces EthGetStorageAtV2 enum and RpcMethod implementation with ExtBlockNumberOrHash parameter. Extracts storage retrieval logic into new async helper get_storage_at(). Refactors existing EthGetStorageAt to delegate to the helper. Adds DESCRIPTION fields for API documentation.
RPC Method Registry src/rpc/mod.rs	Registers EthGetStorageAtV2 in the for_each_rpc_method macro under Eth RPC methods.
Tests and Snapshots src/tool/subcommands/api_cmd/api_compare_tests.rs, src/tool/subcommands/api_cmd/test_snapshots.txt	Adds three new test cases for EthGetStorageAtV2 covering block references (current epoch, safe, finalized). Includes corresponding snapshot files for regression testing.
Changelog CHANGELOG.md	Documents the new RPC v2 method implementation entry.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested reviewers

• hanabi1224
• LesnyRumcajs

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately and concisely describes the primary change: adding V2 support for the Filecoin.EthGetStorageAt RPC method.
Linked Issues check	✅ Passed	The PR implements the RPC v2 method Filecoin.EthGetStorageAt as required by issue #6301, including tests and documentation updates.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing the EthGetStorageAtV2 RPC method: new RPC variant, shared helper logic, tests, test snapshots, and changelog documentation.

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✨ Finishing touches

• 📝 Generate docstrings

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[codecov]

Codecov Report

❌ Patch coverage is 74.19355% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.76%. Comparing base (7254a42) to head (c313444).

Files with missing lines	Patch %	Lines
src/rpc/methods/eth.rs	74.19%	9 Missing and 7 partials ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/rpc/mod.rs	24.47% <ø> (ø)
src/rpc/methods/eth.rs	69.46% <74.19%> (+0.24%)	⬆️

... and 8 files with indirect coverage changes

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