feat(ui): reduce header height and remove model/provider display

- Decrease header constraint from 4 lines to 3.
- Drop rendering of the model and provider label from the header area.

crates/owlen-tui/src/ui.rs

@@ -254,7 +254,7 @@ pub fn render_chat(frame: &mut Frame<'_>, app: &mut ChatApp) {
     };
 
     let mut constraints = vec![
-        Constraint::Length(4), // Header
+        Constraint::Length(3), // Header
         Constraint::Min(8),    // Messages
     ];
 
@@ -1117,13 +1117,6 @@ fn render_header(frame: &mut Frame<'_>, area: Rect, app: &ChatApp) {
             .fg(theme.focused_panel_border)
             .add_modifier(Modifier::BOLD),
     );
-    let model_label = app.active_model_label();
-    let model_with_provider_span = Span::styled(
-        format!("{} ({})", model_label, app.current_provider()),
-        Style::default()
-            .fg(theme.user_message_role)
-            .add_modifier(Modifier::BOLD),
-    );
 
     let header_block = Block::default()
         .borders(Borders::ALL)
@@ -1131,23 +1124,7 @@ fn render_header(frame: &mut Frame<'_>, area: Rect, app: &ChatApp) {
         .style(Style::default().bg(theme.background).fg(theme.text))
         .title(Line::from(vec![title_span]));
 
-    let inner_area = header_block.inner(area);
-
-    let header_text = vec![
-        Line::default(),
-        Line::from(vec![
-            Span::raw(" "),
-            Span::styled("Model (Provider): ", Style::default().fg(theme.placeholder)),
-            model_with_provider_span,
-        ]),
-    ];
-
-    let paragraph = Paragraph::new(header_text)
-        .style(Style::default().bg(theme.background).fg(theme.text))
-        .alignment(Alignment::Left);
-
     frame.render_widget(header_block, area);
-    frame.render_widget(paragraph, inner_area);
 }
 
 fn apply_visual_selection<'a>(