[zfergus]

Description

Fixes Candidates::build (static and CCD overloads) applying mesh.can_collide to the wrong vertices in the codimensional broad-phase passes.

• The vertex–vertex pass and the 3D codim.-edge vs. codim.-vertex pass build the broad phase on a subset of the mesh.
• That broad phase reports subset-local indices (0, 1, 2, …), but can_collide was called on them as if they were mesh vertex ids.
• On any mesh with codim. vertices and a can_collide filter, pairs that should be filtered leaked through and allowed pairs were dropped.

Fix

• Translate subset-local ids to mesh vertex ids before calling the filter. The edge–vertex pass maps its combined vertex list (codim. vertices, then codim. edges' vertices) the same way.
• Restore broad_phase->can_vertices_collide = mesh.can_collide after each pass, since the temporary filters capture locals.

Impact

• No API changes.
• Meshes without codim. vertices or without a filter behave as before.
• Meshes that use both now get the filtering they asked for.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• New regression test "Collision filter applies to codimensional vertices by mesh vertex id" ([candidates][codim][filter]): 52 assertions. It fails 12 of them on main and passes with this change.
• ipc_toolkit_tests "[candidates],[codim] ~[!benchmark]": all pass (3951 assertions in 19 test cases).

Test Configuration:

• OS and Version: macOS (Darwin 27.2.0)
• Compiler and Version: AppleClang 21.0, C++17, Debug (test preset)

Checklist

• My code follows the clang-format style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.87%. Comparing base (3dd025f) to head (064a5d1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #303   +/-   ##
=======================================
  Coverage   96.86%   96.87%           
=======================================
  Files         229      229           
  Lines       23047    23075   +28     
  Branches     1619     1619           
=======================================
+ Hits        22325    22353   +28     
  Misses        722      722           

Flag	Coverage Δ
unittests	96.87% <100.00%> (+<0.01%)	⬆️

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