Fix TUI layout for halfwidth Japanese sound marks (#35962)

## What changed

- Use Ratatui-compatible terminal widths throughout TUI layout, preserving
  full-width counters for long lines.
- Wrap and truncate on grapheme boundaries so halfwidth kana sound marks and
  emoji sequences stay intact.
- Apply the corrected sizing to text input, selection popups, status and
  history cells, Markdown, hyperlinks, and scrollable cloud diffs.

## Testing

- Add focused unit and snapshot coverage for wrapping, truncation, cursor and
  mask alignment, popup columns, status output, session headers, Markdown
  tables, process output, and scrollable diffs.

GitOrigin-RevId: 294ec0bcff743c6bb16d55ec26308524ce741879

codex-rs/Cargo.lock

@@ -2482,6 +2482,7 @@ dependencies = [
  "codex-utils-cli",
  "crossterm",
  "http 1.4.0",
+ "insta",
  "owo-colors",
  "pretty_assertions",
  "ratatui",
@@ -2492,6 +2493,7 @@ dependencies = [
  "tokio-stream",
  "tracing",
  "tracing-subscriber",
+ "unicode-segmentation",
  "unicode-width 0.2.1",
 ]