fix: enable DEBUG logging for seaweed.hdfs package

Added explicit log4j configuration:
  log4j.logger.seaweed.hdfs=DEBUG

This ensures ALL logs from SeaweedFileSystem and SeaweedHadoopOutputStream
will appear in test output, including our diagnostic logs for position tracking.

Without this, the generic 'seaweed=INFO' setting might filter out
DEBUG level logs from the HDFS integration layer.

test/java/spark/src/test/resources/log4j.properties

@@ -11,6 +11,8 @@ log4j.appender.console.layout.ConversionPattern=%d{yy/MM/dd HH:mm:ss} %p %c{1}:
 log4j.logger.org.apache.spark=WARN
 log4j.logger.org.apache.hadoop=WARN
 log4j.logger.seaweed=INFO
+# Enable DEBUG for SeaweedFS HDFS integration to see position tracking
+log4j.logger.seaweed.hdfs=DEBUG
 # Enable DEBUG for SeaweedFS client to see file size calculations
 log4j.logger.seaweedfs.client.SeaweedRead=DEBUG
 log4j.logger.seaweedfs.client.SeaweedOutputStream=DEBUG