Refresh Rust tooling baseline

[dudetru25]

Summary

• format the native Rust workspace with the repository-pinned Rust 1.94.1 toolchain
• remove the obsolete advisories.unsound cargo-deny key while preserving version-2 advisory enforcement
• establish a clean baseline for the dedicated rug-boring-1 Firecracker builder

There are no semantic Rust changes in this PR: the 30 Rust files are byte-for-byte identical to cargo fmt output. The only policy-file change is the obsolete cargo-deny key removal.

Verification

• cargo fmt --check
• cargo check --locked
• 58 native unit tests passed (1 ignored)
• repository CI clippy profile passed with -D warnings
• locked metadata and Linux X11/Wayland feature policy passed
• cargo audit passed (4 allowed unmaintained warnings)
• cargo deny check advisories bans licenses sources passed
• native third-party notices regenerated without diff
• patch independently reviewed as formatting-only plus the cargo-deny compatibility change
• exact patch applied and verified inside the dedicated Firecracker/WispKey lifecycle on rug-boring-1

Platform boundary

Unity-Unterm's native Unity plugin remains macOS/Windows-only today. The Linux worker validates the portable Rust and supply-chain gates; a Linux native rendering/Unity backend remains separate future work.

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