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/chatwidget/agent.rs

@@ -20,7 +20,7 @@ pub(crate) fn spawn_agent(
 ) -> UnboundedSender<Op> {
     let (codex_op_tx, mut codex_op_rx) = unbounded_channel::<Op>();
 
-    let app_event_tx_clone = app_event_tx.clone();
+    let app_event_tx_clone = app_event_tx;
     tokio::spawn(async move {
         let NewConversation {
             conversation_id: _,
@@ -71,7 +71,7 @@ pub(crate) fn spawn_agent_from_existing(
 ) -> UnboundedSender<Op> {
     let (codex_op_tx, mut codex_op_rx) = unbounded_channel::<Op>();
 
-    let app_event_tx_clone = app_event_tx.clone();
+    let app_event_tx_clone = app_event_tx;
     tokio::spawn(async move {
         // Forward the captured `SessionConfigured` event so it can be rendered in the UI.
         let ev = codex_core::protocol::Event {