chore: remove unused imports and dead code

apply_sync.py

@@ -159,11 +159,10 @@ def main():
     # Auto-launch verify_sync in full mode
     verify_script = os.path.join(os.path.dirname(os.path.abspath(__file__)), "verify_sync.py")
     if os.path.exists(verify_script):
-        import subprocess as _sp
         verify_cmd = [sys.executable, verify_script, "--config", args.config or "config.toml",
                       "--lag", f"{args.lag:.6f}", "--mode", "full"]
         print(f"Launching verify: {' '.join(verify_cmd)}")
-        _sp.Popen(verify_cmd)
+        subprocess.Popen(verify_cmd)
 
     sys.exit(0)