fix(tui): quick wins batch — version footer, column widths, zebra, sparkline

- Show version in dashboard footer (wired from goreleaser ldflags)
- Cap name column at 35, raise sparkline minimum to 15 chars
- Preserve zebra background on group rows (was lost by style override)
- Group sparkline uses bullet • instead of heavy circle ●

internal/tui/table_helpers.go

@@ -66,6 +66,9 @@ func (m Model) renderTable(headers []string, items int, buildRows func(start, en
 			if styleOverride != nil {
 				if s := styleOverride(row, col); s != nil {
 					style := *s
+					if row%2 == 1 {
+						style = style.Background(tableZebraStyle.GetBackground())
+					}
 					if isSelected {
 						style = tableSelectedStyle.Foreground(s.GetForeground())
 					}