chore: enable clippy::redundant_clone (#3489)

Created this PR by:

- adding `redundant_clone` to `[workspace.lints.clippy]` in
`cargo-rs/Cargol.toml`
- running `cargo clippy --tests --fix`
- running `just fmt`

Though I had to clean up one instance of the following that resulted:

```rust
let codex = codex;
```

codex-rs/tui/src/app.rs

@@ -304,7 +304,7 @@ impl App {
     }
 
     pub(crate) fn token_usage(&self) -> codex_core::protocol::TokenUsage {
-        self.chat_widget.token_usage().clone()
+        self.chat_widget.token_usage()
     }
 
     async fn handle_key_event(&mut self, tui: &mut tui::Tui, key_event: KeyEvent) {