fix emoji spacing (#2735)

before:
<img width="295" height="266" alt="Screenshot 2025-08-26 at 5 05 03 PM"
src="https://github.com/user-attachments/assets/3e876f08-26d0-407e-a995-28fd072e288f"
/>

after:
<img width="295" height="129" alt="Screenshot 2025-08-26 at 5 05 30 PM"
src="https://github.com/user-attachments/assets/2a019d52-19ed-40ef-8155-4f02c400796a"
/>

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__interrupt_exec_marks_failed.snap

@@ -3,4 +3,4 @@ source: tui/src/chatwidget/tests.rs
 expression: exec_blob
 ---
 >_
-  ✗ ⌨️  sleep 1
+  ✗ ⌨️ sleep 1

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

@@ -1246,7 +1246,7 @@ fn stream_error_is_rendered_to_history() {
     let cells = drain_insert_history(&mut rx);
     assert!(!cells.is_empty(), "expected a history cell for StreamError");
     let blob = lines_to_single_string(cells.last().unwrap());
-    assert!(blob.contains("⚠  "));
+    assert!(blob.contains("⚠\u{200A} "));
     assert!(blob.contains("stream error:"));
     assert!(blob.contains("idle timeout waiting for SSE"));
 }