Fix U3000 filter labels and hidden previews

[vortexopenclaw]

Summary

• Hide Thinkware .TWSYS internals from scan traversal so preview JPGs do not surface as copyable photos or unknown-channel items.
• Limit Recording Types and Channels filters to actual footage clips, while photos and GPS stay controlled by their dedicated toggles.
• Display continuous recordings as Driving and front/rear channels as Front/Rear.
• Add a smoke regression for U3000 Pro F/R clips plus hidden .TWSYS preview JPGs.

Validation

• swift build
• swift run DashcamOffloader --smoke-test
• git diff --check

Note: origin/main does not include the --scan-source diagnostic command yet, so live-card CLI scan was not available on this focused branch.