Refactor kafka to pure Go (franz-go), fix DBC stubs, update Dockerfile

pkg/kafka/util.go

@@ -0,0 +1,8 @@
+package kafka
+
+import "time"
+
+// durationMs converts milliseconds to time.Duration
+func durationMs(ms int) time.Duration {
+	return time.Duration(ms) * time.Millisecond
+}