Clibration fixes

[samaloney]

• Correct ELUT correction
• Make sure area units carry over to meta pixels

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 64.25%. Comparing base (73f8d02) to head (ec8fa48).
Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
stixpy/calibration/visibility.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #101   +/-   ##
=======================================
  Coverage   64.25%   64.25%           
=======================================
  Files          29       29           
  Lines        1757     1757           
=======================================
  Hits         1129     1129           
  Misses        628      628           

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