perf(lambda-rs): Avoid cloning vertices and attributes when building meshes

[vmarcella]

Summary

Refactors MeshBuilder to use by-value chaining and makes build(self) consume the builder, eliminating O(n) clones of vertex/attribute buffers during mesh finalization.

Related Issues

• N/A

Changes

• Updated MeshBuilder builder methods to take/return Self (with_capacity, with_vertex, with_attributes) and changed build to build(self) -> Mesh.
• Updated call sites (demos + lambda-obj-loader) to use by-value chaining / folds.
• Updated docs/tutorial snippets.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (updates to docs, specs, tutorials, or comments)
• Refactor (code change that neither fixes a bug nor adds a feature)
• Performance (change that improves performance)
• Test (adding or updating tests)
• Build/CI (changes to build process or CI configuration)

Affected Crates

• lambda-rs
• lambda-rs-platform
• lambda-rs-args
• lambda-rs-logging
• Other: lambda-demos-render, lambda-demos-physics, lambda-obj-loader, docs

Checklist

• Code follows the repository style guidelines (cargo +nightly fmt --all) (not run)
• Code passes clippy (cargo clippy --workspace --all-targets -- -D warnings) (not run)
• Tests pass (cargo test --workspace) (not run)
• New code includes appropriate documentation
• Public API changes are documented
• Breaking changes are noted in this PR description

Testing

Commands run:

cargo test -p lambda-rs
cargo check -p lambda-demos-render -p lambda-demos-physics -p lambda-obj-loader

Manual verification steps (if applicable):

1. N/A

Screenshots/Recordings

N/A

Platform Testing

• macOS
• Windows
• Linux

Additional Notes

[github-actions]

✅ Coverage Report

📊 View Full HTML Report (download artifact)

Overall Coverage

Metric	Value
Total Line Coverage	76.73%
Lines Covered	12529 / 16329

Changed Files in This PR

File	Coverage	Lines
crates/lambda-rs-args/src/lib.rs	75.35%	743/986
crates/lambda-rs/src/render/mesh.rs	94.17%	113/120

PR Files Coverage: 77.39% (856/1106 lines)

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_{Last updated: 2026-03-06 04:10:52 UTC · Commit: 84d86f7}