Since the OP stated they used DeepSeek V4 Flash for generating a lot of the code, I decided to check whether there were any outdated dependencies. In my experience, with Rust projects, if you do not instruct models (even Claude 4.7 Opus) to use `cargo add` instead of manually editing the Cargo.toml, you will almost certainly get out-of-date dependencies added to your project.
Manually checking the dependencies used by this project, I was pleased to see they are all the latest version. That doesn't mean there are no issues lurking in transitive dependencies, of course.
As for getting an LLM to review the code, I think we can get all opinionated very fast. For instance, when I was eyeballing the code, some of the enum methods converting to/from strings made me think "this could've been a single #[derive] with strum." That would make the code in provider.rs a lot more concise, at the cost of importing one crate (with no dependencies!)
Lastly, for fun, I decided to get DeepSeek V4 Pro (with Max thinking) to "audit" the codebase. The output mentioned no obvious signs of hidden telemetry, but it did note that the project sets the panic handler to "abort", which I have strong opinions on... Presumably the OP wanted to avoid linking against libunwind to save a few kilobytes of binary size, but now you have a binary that immediately aborts and doesn't give the user a stacktrace of what just crashed. I would rather have a ~50 KiB larger binary if it means getting useful debug info during a panic. Additionally, if there are async tasks that panic, they can't be recovered to display a generic error message; instead the whole process just aborts.