Port the remaining high-level CLI option, validation, environment, terminal-safety, and file-stat compatibility paths into Rust while keeping the existing C file-I/O ABI boundary. Match upstream quiet-mode warnings and exact error text for size and level handling.
Test Plan:
- cargo test --manifest-path rust/cli/Cargo.toml (90 passed)
- cargo clippy --manifest-path rust/Cargo.toml
- cargo clippy --manifest-path rust/Cargo.toml --benches
- cargo clippy --manifest-path rust/Cargo.toml --tests
- make -B -C tests -j2 test-cli-tests (41 passed)