remove conversation history widget (#1727)

this widget is no longer used.

codex-rs/tui/src/text_block.rs

@@ -1,4 +1,3 @@
-use crate::cell_widget::CellWidget;
 use ratatui::prelude::*;
 
 /// A simple widget that just displays a list of `Line`s via a `Paragraph`.
@@ -13,20 +12,3 @@ impl TextBlock {
         Self { lines }
     }
 }
-
-impl CellWidget for TextBlock {
-    fn height(&self, width: u16) -> usize {
-        // Use the same wrapping configuration as ConversationHistoryWidget so
-        // measurement stays in sync with rendering.
-        ratatui::widgets::Paragraph::new(self.lines.clone())
-            .wrap(crate::conversation_history_widget::wrap_cfg())
-            .line_count(width)
-    }
-
-    fn render_window(&self, first_visible_line: usize, area: Rect, buf: &mut Buffer) {
-        ratatui::widgets::Paragraph::new(self.lines.clone())
-            .wrap(crate::conversation_history_widget::wrap_cfg())
-            .scroll((first_visible_line as u16, 0))
-            .render(area, buf);
-    }
-}