Changes made for Pathfinder V5 PC's.

Added two timing measurements in UsbDriveBackup.cs:

Zip Creation (line 142-146) — times CreateAutoBackupArchive() and also logs the archive size in MB File Copy to USB (line 205-207) — times File.Copy() inside the background thread Both log to logfile.txt with the [Startup Timing] prefix. Note the copy runs on a background thread so its timing entry will appear asynchronously in the log.