ApiVersions Matrix Accuracy completed:
## Critical Fixes
- **OffsetFetch API**: Updated advertised from v0-v2 to v0-v5 (MAJOR fix)
- Implementation already supported v3+ throttle_time_ms and v5+ leader_epoch
- Clients can now use advanced OffsetFetch features
- **CreateTopics API**: Updated advertised from v0-v4 to v0-v5 (minor fix)
- Implementation already routed v5 requests to v2+ handler
- Better client compatibility for v5 CreateTopics requests
## Implementation
- **handleApiVersions()**: Corrected advertised max versions
- **validateAPIVersion()**: Updated validation ranges to match advertisements
- **Consistency**: Eliminated mismatch between advertised vs implemented versions
## Testing & Verification
- **Comprehensive test suite**: 6 new tests in api_versions_test.go
- **Version validation tests**: OffsetFetch v3-v5 and CreateTopics v5 now accepted
- **End-to-end verification**: E2E tests still pass, no regressions
- **API audit documentation**: Complete version matrix in API_VERSION_MATRIX.md
## Impact
- **Client compatibility**: Higher-version clients can now connect properly
- **Feature utilization**: Advanced features like leader epoch, throttle time accessible
- **Protocol compliance**: Advertised versions now match actual implementation
- **Future-proofing**: Clear process for managing API version accuracy
Ready for Phase 4: Consumer group protocol metadata parsing
