Add unsafe versions of foreach_neighbor and foreach_point_neighbor

[efaulhaber]

Add unsafe versions of foreach_neighbor and foreach_point_neighbor that skip all bounds checks.

Once again citing @sloede:

We like "unsafe" if it implies raw speed 😈

[Copilot]

Pull request overview

This PR introduces “unsafe” neighbor-iteration APIs intended to skip bounds checks for performance-critical CPU/GPU loops, and restructures the internal neighbor-loop dispatch to separate a safe function barrier from an inbounds-propagating inner loop.

Changes:

• Add exported foreach_neighbor_unsafe and foreach_point_neighbor_unsafe APIs.
• Introduce a foreach_neighbor_inner function-barrier pattern and update GridNeighborhoodSearch to specialize the inner loop.
• Update documentation and exports to expose the new unsafe entry points.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/neighborhood_search.jl	Adds foreach_point_neighbor_unsafe and foreach_neighbor_unsafe, plus a new foreach_neighbor_inner dispatch layer and updated docs.
src/nhs_grid.jl	Renames the grid specialization to foreach_neighbor_inner and adjusts comments around bounds-check safety.
src/nhs_precomputed.jl	Attempts to adjust the precomputed specialization for the new unsafe/safe split (currently miswired).
src/PointNeighbors.jl	Exports the newly added unsafe APIs.

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[codecov]

Codecov Report

❌ Patch coverage is 96.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 86.06%. Comparing base (41523f7) to head (e3194a6).

Files with missing lines	Patch %	Lines
src/neighborhood_search.jl	94.11%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #154      +/-   ##
==========================================
+ Coverage   84.82%   86.06%   +1.23%     
==========================================
  Files          15       15              
  Lines         725      739      +14     
==========================================
+ Hits          615      636      +21     
+ Misses        110      103       -7     

Flag	Coverage Δ
unit	86.06% <96.66%> (+1.23%)	⬆️

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