P1 and A1 series printers serve JPEG frames on port 6000 over TLS, behind
the same access code. This adds the connection, a frame reader, and
POST /api/printers/:id/camera/test, which waits for one picture and says
what arrived — enough to find out whether the camera answers before any
viewer is built.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
