feat(tui): ntcharts latency line chart in inline detail panel

Replace block-element sparkline with ntcharts streamline chart in the
inline detail panel. Renders a 4-row line chart with thin line style
using the theme accent color. Auto-scales Y axis to latency range.

Added github.com/NimbleMarkets/ntcharts v0.5.1 dependency (lipgloss v1
compatible). Min/Avg/Max stats rendered below the chart.

internal/tui/update.go

@@ -142,7 +142,7 @@ func (m *Model) handleFormMsg(msg tea.Msg) (tea.Model, tea.Cmd) {
 	return m, nil
 }
 
-const detailInlineHeight = 8
+const detailInlineHeight = 12
 
 func (m *Model) recalcLayout() {
 	chrome := chromeBase