feat(#246): add tie-handling tests for dispute voting

[Kingsman-99]

• test_two_way_tie_returns_no_majority
• test_three_way_tie_at_top_returns_no_majority
• test_all_outcomes_tied_returns_no_majority
• test_exact_60_percent_is_not_a_tie (boundary guard)
• test_admin_fallback_allowed_after_tie

Updated .gitignore to exclude snapshots, build artifacts, Cargo.lock

Pull Request

📋 Description

Brief description of the changes in this PR.

🎯 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
• Code refactoring
• Test addition/update
• CI/CD update

🔗 Related Issues

Closes #246

📝 Changes Made

• Change 1
• Change 2
• Change 3

🧪 Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• All tests passing locally
• Test coverage maintained/improved

Manual Testing

• Tested on testnet
• Tested locally
• Edge cases tested

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By submitting this PR, I confirm that:

• I have read and followed the CONTRIBUTING.md guidelines
• My code follows the project's coding standards
• I have tested my changes thoroughly
• I am ready for code review

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