feat: make reasoning effort/summaries configurable (#1199)

Previous to this PR, we always set `reasoning` when making a request
using the Responses API:


d7245cbbc9/codex-rs/core/src/client.rs (L108-L111)

Though if you tried to use the Rust CLI with `--model gpt-4.1`, this
would fail with:

```shell
"Unsupported parameter: 'reasoning.effort' is not supported with this model."
```

We take a cue from the TypeScript CLI, which does a check on the model
name:


d7245cbbc9/codex-cli/src/utils/agent/agent-loop.ts (L786-L789)

This PR does a similar check, though also adds support for the following
config options:

```
model_reasoning_effort = "low" | "medium" | "high" | "none"
model_reasoning_summary = "auto" | "concise" | "detailed" | "none"
```

This way, if you have a model whose name happens to start with `"o"` (or
`"codex"`?), you can set these to `"none"` to explicitly disable
reasoning, if necessary. (That said, it seems unlikely anyone would use
the Responses API with non-OpenAI models, but we provide an escape
hatch, anyway.)

This PR also updates both the TUI and `codex exec` to show `reasoning
effort` and `reasoning summaries` in the header.

codex-rs/core/src/codex.rs

@@ -108,6 +108,8 @@ impl Codex {
         let configure_session = Op::ConfigureSession {
             provider: config.model_provider.clone(),
             model: config.model.clone(),
+            model_reasoning_effort: config.model_reasoning_effort,
+            model_reasoning_summary: config.model_reasoning_summary,
             instructions,
             approval_policy: config.approval_policy,
             sandbox_policy: config.sandbox_policy.clone(),
@@ -554,6 +556,8 @@ async fn submission_loop(
             Op::ConfigureSession {
                 provider,
                 model,
+                model_reasoning_effort,
+                model_reasoning_summary,
                 instructions,
                 approval_policy,
                 sandbox_policy,
@@ -575,7 +579,12 @@ async fn submission_loop(
                     return;
                 }
 
-                let client = ModelClient::new(model.clone(), provider.clone());
+                let client = ModelClient::new(
+                    model.clone(),
+                    provider.clone(),
+                    model_reasoning_effort,
+                    model_reasoning_summary,
+                );
 
                 // abort any current running session and clone its state
                 let retain_zdr_transcript =