Refactor: Extract grid logic out of DecompressionPlanner

[Rolf-Smit]

Moved grid-related state and methods into a standalone DecoGrid class. DecompressionPlanner now accepts a DecoGrid instance and delegates grid operations to it.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.00000% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.78%. Comparing base (72b9e98) to head (85e8db8).

Files with missing lines	Patch %	Lines
...ysner/domain/decompression/DecompressionPlanner.kt	81.81%	0 Missing and 4 partials ⚠️
...otech/app/abysner/domain/decompression/DecoGrid.kt	92.68%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #172      +/-   ##
==========================================
+ Coverage   69.77%   69.78%   +0.01%     
==========================================
  Files         141      142       +1     
  Lines        7576     7580       +4     
  Branches      933      933              
==========================================
+ Hits         5286     5290       +4     
  Misses       1813     1813              
  Partials      477      477              

Flag	Coverage Δ
domain	77.73% <90.00%> (+0.05%)	⬆️
presentation	67.82% <ø> (ø)

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