v3.42.35: Standardize TUI title prefixes for consistency

- [CHECK] for diagnosis, previews, validations
- [STATS] for status, history, metrics views
- [SELECT] for selection/browsing screens
- [EXEC] for execution screens (backup/restore)
- [CONFIG] for settings/configuration

Fixed 8 files with inconsistent prefixes:
- diagnose_view.go: [SEARCH] → [CHECK]
- settings.go: [CFG] → [CONFIG]
- menu.go: [DB] → clean title
- history.go: [HISTORY] → [STATS]
- backup_manager.go: [DB] → [SELECT]
- archive_browser.go: [PKG]/[SEARCH] → [SELECT]
- restore_preview.go: added [CHECK]
- restore_exec.go: [RESTORE] → [EXEC]

internal/tui/history.go

@@ -191,7 +191,7 @@ func (m HistoryViewModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 func (m HistoryViewModel) View() string {
 	var s strings.Builder
 
-	header := titleStyle.Render("[HISTORY] Operation History")
+	header := titleStyle.Render("[STATS] Operation History")
 	s.WriteString(fmt.Sprintf("\n%s\n\n", header))
 
 	if len(m.history) == 0 {