filter: add dilate and feature filter

[imagejan]

Closes #64.
Closes #65.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 92.85714% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 98.20%. Comparing base (568e036) to head (39d01e7).

Files	Patch %	Lines
src/faim_wako_searchfirst/filter.py	80.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #66      +/-   ##
==========================================
- Coverage   98.61%   98.20%   -0.42%     
==========================================
  Files           9       10       +1     
  Lines         361      389      +28     
  Branches       44       48       +4     
==========================================
+ Hits          356      382      +26     
- Misses          2        3       +1     
- Partials        3        4       +1     

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