Run custom lints during PR/CI

Using [dylint](https://github.com/trailofbits/dylint) or similar, we need to write some lints to help catch issues against guidelines early when the dev is most likely to do something about it.

It'd be nice to run them during the inner loop, but rust-analyzer only supports a single linter (we configure this to be clippy, which is better than the default `cargo check`) and I'd rather run that then our few (by comparison) lints. There is a way to have custom lints run clippy, but there's a maintenance burden of keeping the verison in check with the toolchain, which means we'd also have to dictate a particular toolchain version that makes our existing PR/CI process more difficult (have to override each command or at least each job via `rustup`).

Start by reviewing the repository's existing PR/CI jobs and the proposed dylint approach, including how clippy and the Rust toolchain are currently configured. Done means the custom lints run during PR/CI without requiring a burdensome fixed toolchain version or disrupting the existing workflow.

Written by the indexing model from the issue text.