fix binning halving bug in snapshot template

- Don't fall back to cam.xystart/xyend (binned coords) when set_window
  expects unbinned: caused progressive pixel-count halving each exposure
- Fix int vs [int,int] binning comparison so ArtemisBin isn't called
  redundantly on every exposure

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>