fix: replace manual ABI decoding with web3.py in GovernanceEthereum

[Wanbogang]

This pull request fixes the fragility and testability issues identified in issue #1824.

Problem

The previous implementation used manual hex parsing in decode_eth_response which was:

• Fragile to minor data format variations
• Difficult to test reliably
• Prone to silent failures

Solution

Replaced manual ABI decoding with web3.py contract calls:

• Removed fragile decode_eth_response function with manual hex parsing
• Use web3.py contract.functions.getRuleSet().call() for robust ABI decoding
• Defined minimal ABI for the getRuleSet function
• Added comprehensive error handling for BadFunctionCallOutput and ContractLogicError

Improved test coverage:

• Achieved 100% code coverage with 22 comprehensive tests
• Mocked web3.py interactions properly
• Added tests for error scenarios and edge cases
• Added integration tests for full workflow

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

[openminddev]

Please don't change the test file name

[Wanbogang]

Please don't change the test file name

noted
OK, I will do it

[Wanbogang]

Hi @openminddev

tests/inputs/
├── base/
│ ├── init.py
│ └── test_governance_ethereum.py ← The file that has an error in CI/CD
└── plugins/
├── init.py
└── test_ethereum_governance.py ← The files I updated

I have a question regarding the test structure for ethereum_governance.py:

Current situation:

• Source file: src/inputs/plugins/ethereum_governance.py
• Test file 1: tests/inputs/plugins/test_ethereum_governance.py ✅
• Test file 2: tests/inputs/base/test_governance_ethereum.py ❓

Both test files import and test the same GovernanceEthereum class.

My questions:

1. Should the correct test location be tests/inputs/plugins/? (following the standard mirror structure of source code)
2. Why does CI/CD also run tests from tests/inputs/base/?
3. Are these two test files intentionally separate (for different purposes), or is this an accidental duplication across folders?

Current PR status:

• I've updated tests/inputs/plugins/test_ethereum_governance.py with web3.py implementation and 100% coverage
• The file in tests/inputs/base/ still expects the old implementation (aiohttp, decode_eth_response)
• This causes CI/CD failures because it tests non-existent attributes