Improve `cargo not found` error message, closes #4428

Editor assessment

This is a model conventional commit for a developer-experience improvement: `feat(cli)` accurately signals new user-visible behavior (a better error message), and quoting `cargo not found` makes the subject instantly concrete. It's imperative, lowercase, and just over 70 characters with both issue and PR references included—borderline for GitHub truncation but acceptable. Referencing the closing issue inline reads like a misplaced footer, though many tooling setups parse it fine. The absence of a body is forgivable here since the change is small and self-explanatory, but one line describing the new wording would help changelog readers. Solid, scannable, and automation-friendly overall.