Fix memory leaks and fill bug in EWA resampling

[djhoese]

While working on some C++ optimizations in EWA resampling Claude identified some memory leaks and logic bugs. These are fixed here:

1. Allocated but not freed memory in some cases (mostly error cases)
2. Float 32-bit input fill value not being respected.

• Closes #xxxx
• Tests added
• Tests passed
• Fully documented

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.87%. Comparing base (82b485c) to head (9e2bb3d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #751   +/-   ##
=======================================
  Coverage   93.87%   93.87%           
=======================================
  Files          89       89           
  Lines       13888    13905   +17     
=======================================
+ Hits        13037    13054   +17     
  Misses        851      851           

Flag	Coverage Δ
unittests	93.87% <100.00%> (+<0.01%)	⬆️

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