refactor(tests): Improve test readability by converting batch summaries to individual test cases

[matthewjablack]

Problem

The compatibility tests were using batch summaries that made debugging difficult:

• Aggregate results like "DlcOffer: 14 pass, 0 fail"
• No way to identify which specific test vector failed
• Console logging instead of proper test assertions
• Emoji clutter in test output

Solution

Convert all batch test summaries to individual test cases:

Before:

DlcOffer Serialization Test Results:
Passed: 14/14
Failed: 0/14
✓ should test DlcOffer serialization against all test vectors

After:

✓ should correctly serialize DlcOffer for enum_3_of_3_test.json
✓ should correctly serialize DlcOffer for enum_3_of_5_test.json
✓ should correctly serialize DlcOffer for enum_and_numerical_3_of_5_test.json

Benefits

• Precise debugging: Know exactly which test vector fails
• Targeted testing: npm test -- --grep "enum_3_of_3_test.json"
• Better CI/CD: Individual pass/fail reporting in test runners
• Clean output: Removed emojis, proper expect() assertions
• Code reduction: 408→137 lines (-271 lines, -66% complexity)

Test Coverage

Now provides 127 individual test cases instead of aggregate summaries:

• 42 serialization tests (14 each for Offer/Accept/Sign)
• 42 deserialization tests (14 each for Offer/Accept/Sign)
• 42 cross-language compatibility tests (14 each for Offer/Accept/Sign)
• 6 Rust-CLI compatibility tests (representative samples)

🔍 Testing

# Run all compatibility tests
npm test compatibility

# Test specific test vector
npm test -- --grep "enum_3_of_3_test.json"

# Test specific message type
npm test -- --grep "should correctly serialize DlcOffer"

Each test failure now provides clear context about which test vector and operation failed, dramatically improving debugging experience.