feat: Show captured face thumbnails during registration

[jihanurrahman33]

Implements drawFaces in SessionView to display captured face thumbnails and overrides isCapableOfDrawingFaces to return true for RegistrationSessionSettings.

• Captured images are shown as rounded thumbnails at the bottom of the session view
• Respects getCapturedFaceImageHeight() for sizing
• Clears thumbnails on session start/finish

This aligns the Compose session view with existing controller logic that emits face previews during registration.