debug: verify JARs contain latest code before running tests

CRITICAL ISSUE: Our constructor logs aren't appearing!

Adding verification step to check if SeaweedOutputStream JAR
contains the new 'BASE constructor called' log message.

This will tell us:
1. If verification FAILS → Maven is building stale JARs (caching issue)
2. If verification PASSES but logs still don't appear → Docker isn't using the JARs
3. If verification PASSES and logs appear → Fix is working!

Using 'strings' on the .class file to grep for the log message.

.github/workflows/spark-integration-tests.yml

@@ -114,7 +114,27 @@ jobs:
         echo "Copying Maven artifacts for Docker container..."
         mkdir -p .m2/repository/com
         cp -r ~/.m2/repository/com/seaweedfs .m2/repository/com/
-        echo "OK Maven artifacts ready"
+        echo "OK Maven artifacts copied"
+        
+        echo ""
+        echo "=== VERIFYING NEW CODE IS IN JARS ==="
+        # Check if SeaweedOutputStream contains our new constructor log
+        JAR_PATH=".m2/repository/com/seaweedfs/seaweedfs-client/3.80.1-SNAPSHOT/seaweedfs-client-3.80.1-SNAPSHOT.jar"
+        if [ -f "$JAR_PATH" ]; then
+          if unzip -p "$JAR_PATH" seaweedfs/client/SeaweedOutputStream.class | strings | grep -q "SeaweedOutputStream BASE constructor called"; then
+            echo "OK SeaweedOutputStream contains new constructor log"
+          else
+            echo "ERROR SeaweedOutputStream JAR is STALE - does not contain constructor log!"
+            echo "Listing JAR contents:"
+            unzip -l "$JAR_PATH" | grep SeaweedOutputStream
+            exit 1
+          fi
+        else
+          echo "ERROR JAR not found at $JAR_PATH"
+          ls -la .m2/repository/com/seaweedfs/seaweedfs-client/3.80.1-SNAPSHOT/
+          exit 1
+        fi
+        echo "OK Maven artifacts ready and verified"
 
     - name: Run Spark integration tests
       working-directory: test/java/spark