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/core/src/codex.rs

@@ -214,12 +214,7 @@ impl Codex {
         let conversation_id = session.conversation_id;
 
         // This task will run until Op::Shutdown is received.
-        tokio::spawn(submission_loop(
-            session.clone(),
-            turn_context,
-            config,
-            rx_sub,
-        ));
+        tokio::spawn(submission_loop(session, turn_context, config, rx_sub));
         let codex = Codex {
             next_id: AtomicU64::new(0),
             tx_sub,
@@ -1074,7 +1069,7 @@ impl AgentTask {
                 id: self.sub_id,
                 msg: EventMsg::TurnAborted(TurnAbortedEvent { reason }),
             };
-            let sess = self.sess.clone();
+            let sess = self.sess;
             tokio::spawn(async move {
                 sess.send_event(event).await;
             });
@@ -1772,7 +1767,7 @@ async fn try_run_turn(
                 }
             })
             .map(|call_id| ResponseItem::CustomToolCallOutput {
-                call_id: call_id.clone(),
+                call_id,
                 output: "aborted".to_string(),
             })
             .collect::<Vec<_>>()
@@ -1792,7 +1787,7 @@ async fn try_run_turn(
         cwd: turn_context.cwd.clone(),
         approval_policy: turn_context.approval_policy,
         sandbox_policy: turn_context.sandbox_policy.clone(),
-        model: turn_context.client.get_model().clone(),
+        model: turn_context.client.get_model(),
         effort: turn_context.client.get_reasoning_effort(),
         summary: turn_context.client.get_reasoning_summary(),
     });
@@ -3154,7 +3149,7 @@ mod tests {
             exit_code: 0,
             stdout: StreamOutput::new(String::new()),
             stderr: StreamOutput::new(String::new()),
-            aggregated_output: StreamOutput::new(full.clone()),
+            aggregated_output: StreamOutput::new(full),
             duration: StdDuration::from_secs(1),
         };
 
@@ -3188,7 +3183,7 @@ mod tests {
     fn model_truncation_respects_byte_budget() {
         // Construct a large output (about 100kB) so byte budget dominates
         let big_line = "x".repeat(100);
-        let full = std::iter::repeat_n(big_line.clone(), 1000)
+        let full = std::iter::repeat_n(big_line, 1000)
             .collect::<Vec<_>>()
             .join("\n");