Enable clippy linting in repo

https://github.com/rust-lang/rust-clippy We use it in air: https://github.com/posit-dev/air/blob/main/clippy.toml And it's used in most major Rust projects: - https://github.com/biomejs/biome/blob/main/clippy.toml - https://github.com/rust-lang/rust-analyzer/blob/master/clippy.toml - https://github.com/astral-sh/ruff/blob/main/clippy.toml - https://github.com/zed-industries/zed/blob/main/clippy.toml In addition to linting towards conventional style conventions, it also makes it possible to disallow use of certain methods, functions, or types, which could be handy in the future (see clippy.toml files above for examples of this). We could disallow `.unwrap()` and `.expect()` in favour of `log_err` or explicit `panic` for instance.