fix: enable text selection, dashboard multi-column layout

- Remove WithMouseCellMotion to allow text selection in terminal
- Dashboard now uses 2-column layout (left: system/tools, right: actions/status)
- More compact dashboard with better space usage

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

cmd/muyue/main.go

@@ -108,7 +108,7 @@ func runTUI() {
 	result := scanner.ScanSystem()
 
 	model := tui.NewModel(cfg, result)
-	p := tea.NewProgram(model, tea.WithAltScreen(), tea.WithMouseCellMotion())
+	p := tea.NewProgram(model, tea.WithAltScreen())
 
 	if _, err := p.Run(); err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %v\n", err)