Integrate Find with transcript selection mode (#57222)

## What changed

- Support `/` to open Find in selection mode and `Enter` to move the cursor to the match, extending an active selection.
- Repeat the accepted search from the cursor with `n` for older matches and `Shift+n` for newer matches. Cancel pending repeats when the cursor or selection changes.
- Restore the previous search, cursor, and selection when cancelling a new search, and reuse the previous search when accepting an empty query.
- Align the cursor to selectable graphemes and preserve expanded matches when leaving selection mode.

## Testing

Add regression coverage for search acceptance and cancellation, repeated searches, Unicode cursor placement, expanded output retention, and history pages loaded while a search is saved.

GitOrigin-RevId: 077be52a54d5e006f65eacc4634baf8c089d3662

codex-rs/tui/src/transcript_view/input.rs

@@ -202,6 +202,21 @@ impl TranscriptView {
             return Some(action);
         }
         if self.select_mode.is_some() {
+            if self.is_search_editing() {
+                let (code, modifiers) =
+                    crate::key_hint::normalize_key_parts(key.code, key.modifiers);
+                let accepting = code == KeyCode::Enter && modifiers == KeyModifiers::NONE;
+                let cancelling = code == KeyCode::Esc
+                    || (code == KeyCode::Char('c') && modifiers == KeyModifiers::CONTROL);
+                if self.handle_search_key(key, cells) {
+                    if accepting && self.search.is_reading() {
+                        self.accept_search_into_select_mode(cells);
+                    } else if cancelling {
+                        self.restore_select_search_origin();
+                    }
+                    return Some(ViewAction::Changed);
+                }
+            }
             return self
                 .handle_select_mode_key(key, cells)
                 .or(Some(ViewAction::Changed));