Update implementation phases: Phase 4 completed

- Phase 1 ✅: SeaweedMQ record retrieval implemented
- Phase 2 ✅: CreateTopics v0-v5 compliance implemented
- Phase 3 ✅: ApiVersions matrix accuracy fixed (OffsetFetch v0-v5, CreateTopics v0-v5)
- Phase 4 ✅: Consumer group protocol metadata parsing enhanced (ClientHost, robust parsing)
- Ready to start Phase 5: Multi-batch Fetch concatenation support

weed/mq/kafka/IMPLEMENTATION_PHASES.md

@@ -47,19 +47,22 @@
 
 **Verification**: Critical fixes for OffsetFetch v0-v5 and CreateTopics v0-v5 accuracy
 
-## Phase 4: Consumer Group Protocol Metadata (PRIORITY MEDIUM)
+## Phase 4: Consumer Group Protocol Metadata (COMPLETED ✅)
 **Goal**: Proper JoinGroup protocol metadata parsing
 
 ### Tasks:
-- [ ] Implement consumer protocol metadata parsing in JoinGroup
-- [ ] Extract subscription topics and user data from metadata
-- [ ] Populate ClientHost from connection information
-- [ ] Support multiple assignment strategies properly
+- [x] Implement consumer protocol metadata parsing in JoinGroup
+- [x] Extract subscription topics and user data from metadata
+- [x] Populate ClientHost from connection information
+- [x] Support multiple assignment strategies properly
 
-**Files to modify**:
+**Files modified**:
 - `weed/mq/kafka/protocol/joingroup.go`
-- `weed/mq/kafka/protocol/consumer_group_metadata.go` (new file)
-- Add test file: `weed/mq/kafka/protocol/consumer_group_metadata_test.go`
+- `weed/mq/kafka/protocol/handler.go` (connection context)
+- Added file: `weed/mq/kafka/protocol/consumer_group_metadata.go`
+- Added test file: `weed/mq/kafka/protocol/consumer_group_metadata_test.go`
+
+**Verification**: ClientHost shows real IPs; enhanced protocol metadata parsing with 17 tests
 
 ## Phase 5: Multi-Batch Fetch Support (PRIORITY MEDIUM)
 **Goal**: Support multiple record batch concatenation in Fetch responses
@@ -102,7 +105,7 @@
 - All protocol handler files
 - Add test file: `weed/mq/kafka/protocol/error_handling_test.go`
 
-## Current Status: Phase 1, 2 & 3 completed, ready for Phase 4
+## Current Status: Phase 1-4 completed, ready for Phase 5
 
 ### Implementation Notes:
 - Each phase should include comprehensive tests