Add debug-only slash command for rollout path (#5936)

## Summary
- add a debug-only `/rollout` slash command that prints the rollout file
path or reports when none is known
- surface the new command in the slash command metadata and cover it
with unit tests

<img width="539" height="99" alt="image"
src="https://github.com/user-attachments/assets/688e1334-8a06-4576-abb8-ada33b458661"
/>

codex-rs/tui/src/chatwidget/tests.rs

@@ -863,6 +863,42 @@ fn slash_undo_sends_op() {
     }
 }
 
+#[test]
+fn slash_rollout_displays_current_path() {
+    let (mut chat, mut rx, _op_rx) = make_chatwidget_manual();
+    let rollout_path = PathBuf::from("/tmp/codex-test-rollout.jsonl");
+    chat.current_rollout_path = Some(rollout_path.clone());
+
+    chat.dispatch_command(SlashCommand::Rollout);
+
+    let cells = drain_insert_history(&mut rx);
+    assert_eq!(cells.len(), 1, "expected info message for rollout path");
+    let rendered = lines_to_single_string(&cells[0]);
+    assert!(
+        rendered.contains(&rollout_path.display().to_string()),
+        "expected rollout path to be shown: {rendered}"
+    );
+}
+
+#[test]
+fn slash_rollout_handles_missing_path() {
+    let (mut chat, mut rx, _op_rx) = make_chatwidget_manual();
+
+    chat.dispatch_command(SlashCommand::Rollout);
+
+    let cells = drain_insert_history(&mut rx);
+    assert_eq!(
+        cells.len(),
+        1,
+        "expected info message explaining missing path"
+    );
+    let rendered = lines_to_single_string(&cells[0]);
+    assert!(
+        rendered.contains("not available"),
+        "expected missing rollout path message: {rendered}"
+    );
+}
+
 #[test]
 fn undo_success_events_render_info_messages() {
     let (mut chat, mut rx, _op_rx) = make_chatwidget_manual();