Preserve hook trust bypass in codex exec threads (#26434)

Addresses #26383 and #26452

## Summary

`codex exec --dangerously-bypass-hook-trust` printed the bypass warning,
but valid untrusted hooks still did not run.

Exec applied the flag to its initial config, then lost it when
app-server reloaded config for the new or resumed thread.

## Fix

Forward `bypass_hook_trust: true` through the existing thread request
config override for both start and resume.

The override is omitted when the flag is not enabled, preserving normal
trust behavior.

## Testing

Added:

- A test confirming start and resume preserve the override.
- An end-to-end exec test confirming a `SessionStart` hook runs and
creates a marker file.

codex-rs/exec/tests/suite/hooks.rs

@@ -0,0 +1,44 @@
+#![cfg(not(target_os = "windows"))]
+#![allow(clippy::expect_used)]
+
+use core_test_support::responses;
+use core_test_support::test_codex_exec::test_codex_exec;
+use serde_json::json;
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn exec_hook_trust_bypass_runs_session_start_hook() -> anyhow::Result<()> {
+    let test = test_codex_exec();
+    let marker_path = test.home_path().join("session-start-ran");
+    let command = format!("touch {}", marker_path.display());
+    std::fs::write(
+        test.home_path().join("hooks.json"),
+        serde_json::to_vec_pretty(&json!({
+            "hooks": {
+                "SessionStart": [{
+                    "hooks": [{
+                        "type": "command",
+                        "command": command,
+                    }],
+                }],
+            },
+        }))?,
+    )?;
+
+    let server = responses::start_mock_server().await;
+    let body = responses::sse(vec![
+        responses::ev_response_created("response_1"),
+        responses::ev_assistant_message("response_1", "done"),
+        responses::ev_completed("response_1"),
+    ]);
+    responses::mount_sse_once(&server, body).await;
+
+    test.cmd_with_server(&server)
+        .arg("--skip-git-repo-check")
+        .arg("--dangerously-bypass-hook-trust")
+        .arg("run the session start hook")
+        .assert()
+        .success();
+
+    assert!(marker_path.exists(), "session start hook did not run");
+    Ok(())
+}

codex-rs/exec/tests/suite/mod.rs

@@ -5,6 +5,7 @@ mod apply_patch;
 mod approval_policy;
 mod auth_env;
 mod ephemeral;
+mod hooks;
 mod mcp_required_exit;
 mod originator;
 mod output_schema;