fix(tui): remove hardcoded dark-terminal assumptions — theme-agnostic styles

Structural colors that assumed a dark terminal background replaced with
terminal-relative alternatives:

- Footer key labels: bg(DarkGray)+fg(White) → REVERSED modifier
  (terminal's own reverse-video color, adapts to any theme)
- Row selection (normal): bg(DarkGray) → REVERSED modifier
- Row selection (attention): bg(DarkGray)+fg(LightRed) →
  REVERSED|BOLD+fg(Red)
- Status messages: fg(Cyan) → ITALIC|BOLD (cyan is invisible on
  light backgrounds)
- Footer auto-refresh text: fg(Gray) → terminal default

Semantic colors preserved: Red/Green/Yellow/Blue/Magenta for state
indicators work in both dark and light terminals. The attention row
bg(Red)+fg(White) is kept — red=danger is universal.

14 tests, workspace green (0 failures).

crates/colibri-glasspane-tui/src/main.rs

@@ -381,9 +381,7 @@ impl App {
         if let Some((msg, _)) = &self.status_msg {
             lines.push(Line::from(Span::styled(
                 msg,
-                Style::default()
-                    .fg(Color::Cyan)
-                    .add_modifier(Modifier::ITALIC),
+                Style::default().add_modifier(Modifier::ITALIC | Modifier::BOLD),
             )));
         }
 
@@ -475,14 +473,13 @@ impl App {
                 let row_style = if needs_attention(p) {
                     if Some(i) == selected {
                         Style::default()
-                            .bg(Color::DarkGray)
-                            .fg(Color::LightRed)
-                            .add_modifier(Modifier::BOLD)
+                            .add_modifier(Modifier::REVERSED | Modifier::BOLD)
+                            .fg(Color::Red)
                     } else {
                         Style::default().bg(Color::Red).fg(Color::White)
                     }
                 } else if Some(i) == selected {
-                    Style::default().bg(Color::DarkGray)
+                    Style::default().add_modifier(Modifier::REVERSED)
                 } else {
                     Style::default()
                 };
@@ -579,10 +576,7 @@ impl App {
         let key = |label: &str| -> Span {
             Span::styled(
                 format!(" {label}"),
-                Style::default()
-                    .add_modifier(Modifier::BOLD)
-                    .fg(Color::White)
-                    .bg(Color::DarkGray),
+                Style::default().add_modifier(Modifier::BOLD | Modifier::REVERSED),
             )
         };
         let text = Line::from(vec![
@@ -604,7 +598,7 @@ impl App {
             Span::raw(" filter  "),
             key("r"),
             Span::raw(" refresh  "),
-            Span::styled(" auto 2s", Style::default().fg(Color::Gray)),
+            Span::styled(" auto 2s", Style::default()),
         ]);
         f.render_widget(Paragraph::new(text), area);
     }