fix-clippy

[cedricchevalier19]

Fix clippy warnings due to the previous update #317

Mainly:

• numerical constants are now on the type and not in std
• nice shortcut for is_multiple
• cleaning up unsafe interactions.

[Copilot]

Pull request overview

This PR addresses clippy warnings that arose from a previous update (#317). The changes modernize the codebase by adopting newer Rust standard library APIs and cleaning up code quality issues.

Key changes:

• Migrates numerical constants from std::* namespace to associated type constants (e.g., std::f64::MAX → f64::MAX)
• Replaces manual ceiling division with div_ceil() method
• Updates to use is_multiple_of() for cleaner modulo checks
• Adds explicit unsafe blocks within unsafe functions for better safety documentation
• Changes lookup table from const to static to avoid code bloat
• Updates external library API calls (rand, rayon, criterion)

Reviewed changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tools/src/bin/mesh-reorder.rs	Updates rand API from thread_rng() to rng()
tools/mesh-io/ffi/src/lib.rs	Assigns unused return value with explanation comment
src/work_share.rs	Replaces manual ceiling division with div_ceil()
src/topology/mod.rs	Removes unnecessary lifetime annotation via elision
src/nextafter.rs	Migrates floating-point constants to associated constants
src/geometry.rs	Migrates floating-point constants to associated constants
src/cartesian/mod.rs	Uses is_multiple_of() and compound assignment operator
src/algorithms/z_curve.rs	Migrates integer constant to associated constant
src/algorithms/recursive_bisection.rs	Adds explicit unsafe block within unsafe function
src/algorithms/multi_jagged.rs	Uses is_multiple_of() and migrates constants
src/algorithms/kernighan_lin.rs	Adopts let-chain syntax and migrates constants
src/algorithms/k_means.rs	Removes unused hilbert field from settings struct and migrates constants
src/algorithms/hilbert_curve.rs	Changes large lookup table from const to static
src/algorithms.rs	Updates rand API from gen_range() to random_range()
ffi/src/data.rs	Updates rayon API from repeatn() to repeat_n()
benches/rcb_cartesian.rs	Moves black_box import from criterion to std, removes unnecessary reference

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[imrn99]

LGTM