[Bugfix] Ensure radius defaults are applied when BilateralFilter diameter is <= 0

[zacharyvincze]

Description

• Fixes a bug in BilateralFilter where default radius was applied when radius was <= 0, not diameter.
• Adds test cases with the diameter set to <= 0 to ensure that the behavior is as intended.

[Copilot]

Pull request overview

Fixes BilateralFilter’s default-radius logic so the fallback radius is applied only when diameter <= 0 (instead of when the derived radius <= 0), aligning behavior with the intended API semantics and adding regression coverage.

Changes:

• Update radius computation in dispatch_bilateral_filter_border_mode to use the default-radius formula only when diameter <= 0.
• Add Python and C++ test cases that exercise diameter values of 0 and -1.
• Clarify the diameter parameter documentation to describe the radius derivation rules.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/op_bilateral_filter.cpp	Fixes radius selection logic so fallback radius depends on diameter <= 0.
include/op_bilateral_filter.hpp	Documents the updated diameter-to-radius behavior and sigmaSpace clamping.
tests/roccv/python/test_op_bilateral_filter.py	Adds parameterized test inputs with non-positive diameter.
tests/roccv/cpp/src/tests/operators/test_op_bilateral_filter.cpp	Adds CPU/GPU correctness tests for diameter <= 0 cases.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/op_bilateral_filter.cpp	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #144      +/-   ##
===========================================
+ Coverage    74.26%   74.34%   +0.07%     
===========================================
  Files           79       79              
  Lines         3357     3355       -2     
  Branches       738      738              
===========================================
+ Hits          2493     2494       +1     
+ Misses         382      380       -2     
+ Partials       482      481       -1     

Files with missing lines	Coverage Δ
src/op_bilateral_filter.cpp	72.28% <50.00%> (+1.40%)	⬆️

... and 1 file with indirect coverage changes

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