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/cloud-tasks/src/scrollable_diff_tests.rs

@@ -0,0 +1,48 @@
+use super::ScrollableDiff;
+use pretty_assertions::assert_eq;
+
+#[test]
+fn wraps_halfwidth_sound_marks_using_ratatui_width() {
+    let mut diff = ScrollableDiff::new();
+    diff.set_content(vec![
+        "aｶﾞbﾊﾟc".to_string(),
+        "a ﾞb".to_string(),
+        "a ﾟb".to_string(),
+    ]);
+    diff.set_width(/*width*/ 2);
+
+    insta::assert_snapshot!(
+        diff.wrapped_lines().join("\n"),
+        @r"
+        a
+        ｶﾞ
+        b
+        ﾊﾟ
+        c
+        a
+        ﾞb
+        a
+        ﾟb
+        "
+    );
+    assert_eq!(diff.wrapped_src_indices(), [0, 0, 0, 0, 0, 1, 1, 2, 2]);
+}
+
+#[test]
+fn does_not_emit_empty_rows_after_full_width_sound_mark_graphemes() {
+    for grapheme in ["ｶﾞ", "ﾊﾟ"] {
+        let mut diff = ScrollableDiff::new();
+        diff.set_content(vec![format!("a {grapheme} tail")]);
+        diff.set_width(/*width*/ 2);
+
+        let expected = ["a", grapheme, "ta", "il"];
+        let actual = diff
+            .wrapped_lines()
+            .iter()
+            .map(String::as_str)
+            .collect::<Vec<_>>();
+        assert_eq!(actual, expected);
+        assert_eq!(diff.wrapped_src_indices(), [0, 0, 0, 0]);
+        assert_eq!(diff.state.content_h, 4);
+    }
+}