feat: add shared Rust policy templates

[jan-kubica]

Summary

• add source-of-truth Rust formatting, Clippy, Cargo lint, profile, and alias templates
• document copy/sync adoption because Cargo cannot extend these settings from another package
• update the tooling README to include Rust policy templates

Checks

• bun run format
• bun run typecheck
• bun test
• bun run lint
• bun run publint
• bun run pack:dry-run
• python TOML parse check for rust/*.toml
• cargo fmt --all -- --check, cargo clippy --all-targets --all-features -- -D warnings, and cargo test --all-features on a throwaway crate using the templates

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!