[loong10k]

Summary

• Replace RGBA byte chunk iteration with fixed-size array chunks and update Rust 1.99 Clippy assertions across the workspace.
• Fix Rustdoc intra-doc links and pin the API snapshot generator toolchain. The public API snapshot itself is unchanged.
• Refresh Cargo.lock to patched quinn-proto, rustls, rustls-webpki, webpki-roots, and tokio versions; replace the yanked chacha20 release.
• Run security audit on pull requests, collect Clippy diagnostics across targets, and verify the declared Rust 1.88 MSRV for default features.

Verification

• CI #65: all 9 jobs passed on head da66c7b7d9a1b1d750a383f2a897961d22ae4252, including Linux/macOS tests, Clippy, docs, API diff, coverage, examples, and Rust 1.88 default-feature workspace checks and doctests.
• Security Audit #41: cargo audit and cargo deny passed on the same head under the repository's existing audit policy.

Existing MSRV exception

The optional writer-krilla feature is not Rust 1.88 compatible: main already locks krilla 0.8.2, which declares Rust 1.92. An all-features Rust 1.88 check exposed this pre-existing mismatch; this PR does not raise the declared MSRV or change that optional dependency. The new MSRV job verifies the default-feature workspace only.