Add metadata for batch 50

batch_50_metadata.json

@@ -0,0 +1,7 @@
+{
+  "upload_time": "2025-06-23T08:17:03.949977",
+  "total_trees": 501,
+  "new_trees": 10,
+  "batch_number": 50,
+  "upload_interval": 30
+}