PARTIAL FIX: Force kafka-go to use Metadata v4 instead of v6
## Issue Identified:
- kafka-go was using Metadata v6 due to ApiVersions advertising v0-v6
- Our Metadata v6 implementation has format issues causing client failures
- Sarama works because it uses Metadata v4, not v6
## Changes:
- Limited Metadata API max version from 6 to 4 in ApiVersions response
- Added debug test to isolate Metadata parsing issues
- kafka-go now uses Metadata v4 (same as working Sarama)
## Status:
- ✅ kafka-go now uses v4 instead of v6
- ❌ Still has metadata loops (deeper issue with response format)
- ✅ Produce operations work correctly
- ❌ ReadPartitions API still fails
## Next Steps:
- Investigate why kafka-go keeps requesting metadata even with v4
- Compare exact byte format between working Sarama and failing kafka-go
- May need to fix specific fields in Metadata v4 response format
This is progress toward full kafka-go compatibility but more investigation needed.
- Added detailed hex dump comparison between v0 and v1 responses
- Identified v1 adds rack field (2 bytes) and is_internal field (1 byte) = 3 bytes total
- kafka-go still fails with 'multiple Read calls return no data or error'
- Our Metadata v1 format appears correct per protocol spec but incompatible with kafka-go
chrislu