fix: resolve ruff lint errors in scheduler and tests

- scheduler.py: sort import block (I001)
- tests/test_config.py: remove unused os, pytest imports (F401)
- tests/test_upload_tracker.py: remove unused json, os, tempfile imports (F401)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scheduler.py

@@ -1,9 +1,9 @@
 #!/usr/bin/env python3
-import os
-import sys
-import subprocess
-import time
 import logging
+import os
+import subprocess
+import sys
+import time
 from pathlib import Path
 
 try: