The workspace lints deny `clippy::unwrap_used` and `clippy::panic`, but
`command.rs`'s two unit tests used `.unwrap()` and `panic!`, so
`cargo clippy --workspace --all-targets -- -D warnings` (a CI gate)
failed on them. Convert both to the crate's Result-returning test
convention: `CommandIntent::parse(...)?` instead of `.unwrap()`, and a
`return Err(...)` in the let-else instead of `panic!`. Same assertions;
`DomainError` is `thiserror::Error`, so `?` flows into `Box<dyn Error>`.
Workspace clippy --all-targets now reports 0 errors.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>