debug: Add ListOffsets response validation logging

Added comprehensive logging to ListOffsets handler:
- Log when breaking early due to insufficient data
- Log when response count differs from requested count
- Log final response for verification

CRITICAL FINDING: handleListOffsets is NOT being called!

This means the issue is earlier in the request processing pipeline.
The request is reaching the gateway (6 apiKey=2 requests seen),
but handleListOffsets function is never being invoked.

This suggests the routing/dispatching in processRequestSync()
might have an issue or ListOffsets requests are being dropped
before reaching the handler.

Next investigation: Check why APIKeyListOffsets case isn't matching
despite seeing apiKey=2 requests in logs.

weed/mq/kafka/protocol/handler.go

@@ -1917,6 +1917,8 @@ func (h *Handler) handleListOffsets(correlationID uint32, apiVersion uint16, req
 	// Parse minimal request to understand what's being asked (header already stripped)
 	offset := 0
 
+	glog.Warningf("🟡 ListOffsets CALLED: correlationID=%d, apiVersion=%d, requestBodyLen=%d", correlationID, apiVersion, len(requestBody))
+
 	// v1+ has replica_id(4)
 	if apiVersion >= 1 {
 		if len(requestBody) < offset+4 {
@@ -1964,6 +1966,7 @@ func (h *Handler) handleListOffsets(correlationID uint32, apiVersion uint16, req
 	// Process each requested topic
 	for i := uint32(0); i < topicsCount && offset < len(requestBody); i++ {
 		if len(requestBody) < offset+2 {
+			glog.Warningf("🟡 ListOffsets: Breaking at topic %d - insufficient data for name size", i)
 			break
 		}
 
@@ -1972,6 +1975,7 @@ func (h *Handler) handleListOffsets(correlationID uint32, apiVersion uint16, req
 		offset += 2
 
 		if len(requestBody) < offset+int(topicNameSize)+4 {
+			glog.Warningf("🟡 ListOffsets: Breaking at topic %d - insufficient data for name (%d bytes needed, %d available)", i, topicNameSize+4, len(requestBody)-offset)
 			break
 		}
 
@@ -2063,6 +2067,9 @@ func (h *Handler) handleListOffsets(correlationID uint32, apiVersion uint16, req
 	// This prevents ErrIncompleteResponse when request parsing fails mid-way
 	if actualTopicsCount != topicsCount {
 		binary.BigEndian.PutUint32(response[topicsCountOffset:topicsCountOffset+4], actualTopicsCount)
+		glog.Warningf("🟡 ListOffsets: Updated response count from %d to %d, response size=%d", topicsCount, actualTopicsCount, len(response))
+	} else {
+		glog.Infof("🟢 ListOffsets: Response OK - requested %d topics, actual %d, size=%d", topicsCount, actualTopicsCount, len(response))
 	}
 
 	return response, nil