Add area attribute to candidate graph nodes

[cmalinmayor]

Proposed Change

Add the area to the candidate graph nodes by default. Also adds an Area attribute to the NodeAttrs enum, and tests that the area scales with the scaled regionprops implementation.

Checklist

Go through these things before merge. Actions should run automatically to test them, but for information on how to run locally, see CONTRIBUTING.md.

• I have added tests that prove that my feature works in various situations or tests the bugfix (if applicable).
• I have checked that the tests pass and I maintained or improved test coverage (if applicable).
• I have written docstrings and checked that they render correctly in the documentation build.
• I have checked that mypy type checking passes.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.00%. Comparing base (cdc12a4) to head (6ad4d55).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
+ Coverage   86.88%   87.00%   +0.12%     
==========================================
  Files          14       14              
  Lines         427      431       +4     
==========================================
+ Hits          371      375       +4     
  Misses         56       56              

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[AnniekStok]

looks good!