Find people using a reference image

[tulayha]

Allow users to locate appearances of a person by providing a reference image or selecting an existing evidence frame.

Expected behavior:

• Return possible appearances with timestamps and inspectable evidence.
• Keep the similarity score separate from a user-confirmed identity.
• Allow users to confirm or reject matches.
• Reuse the existing face detection and matching code where suitable.
• Make confirmed references reusable for later searches in the same repository.

VidXP should not automatically attach a real-world name to an anonymous face group without user confirmation.