feat(theme): add catppuccin themes with transparency and 256-color support

Add a theme package providing all four catppuccin flavors (mocha,
frappe, macchiato, latte) mapped to the xterm-256 palette. Themes are
selected with -theme or the CTOP_THEME environment variable; -i inverts
the flavor. Background slots use the terminal's native color for
transparency (opt out with -solid / CTOP_SOLID), and termbox is switched
to Output256 so colors render correctly. Replace hardcoded colors in the
compact and single views with ctheme portrait slots.

main.go

@@ -12,6 +12,7 @@ import (
 	"github.com/bcicen/ctop/container"
 	"github.com/bcicen/ctop/cwidgets/compact"
 	"github.com/bcicen/ctop/logging"
+	"github.com/bcicen/ctop/theme"
 	"github.com/bcicen/ctop/widgets"
 	ui "github.com/gizak/termui"
 	tm "github.com/nsf/termbox-go"
@@ -45,6 +46,8 @@ func main() {
 		reverseSortFlag = flag.Bool("r", false, "reverse container sort order")
 		invertFlag      = flag.Bool("i", false, "invert default colors")
 		connectorFlag   = flag.String("connector", "docker", "container connector to use")
+		themeFlag       = flag.String("theme", "", "catppuccin color theme (mocha, frappe, macchiato, latte)")
+		solidFlag       = flag.Bool("solid", false, "paint opaque catppuccin background instead of transparent")
 	)
 	flag.Parse()
 
@@ -85,15 +88,39 @@ func main() {
 		config.Toggle("sortReversed")
 	}
 
+	// resolve catppuccin theme in order: -theme flag, CTOP_THEME env, default
+	themeName := "mocha"
+	switch {
+	case *themeFlag != "":
+		themeName = *themeFlag
+	case os.Getenv("CTOP_THEME") != "":
+		themeName = os.Getenv("CTOP_THEME")
+	}
+	flavor, ok := theme.ParseFlavor(themeName)
+	if !ok {
+		fmt.Printf("invalid theme: %q (available: %s)\n", themeName, strings.Join(theme.Flavors(), ", "))
+		os.Exit(1)
+	}
+	theme.Set(flavor)
+	solid := *solidFlag
+	switch os.Getenv("CTOP_SOLID") {
+	case "1", "true", "TRUE", "yes", "YES":
+		solid = true
+	}
+	theme.SetOpaque(solid)
+
 	// init ui
 	if *invertFlag {
 		InvertColorMap()
+	} else {
+		SetColorMap()
 	}
 	ui.ColorMap = ColorMap // override default colormap
 	if err := ui.Init(); err != nil {
 		panic(err)
 	}
 	tm.SetInputMode(tm.InputAlt)
+	tm.SetOutputMode(tm.Output256) // enable 256-color catppuccin palette
 
 	defer Shutdown()
 	// init grid, cursor, header
@@ -150,6 +177,8 @@ options:
 func printHelp() {
 	fmt.Println(helpMsg)
 	flag.PrintDefaults()
+	fmt.Printf("\ncatppuccin themes: mocha (default), frappe, macchiato, latte\n")
+	fmt.Printf("select a theme with -theme or the CTOP_THEME environment variable\n")
 	fmt.Printf("\navailable connectors: ")
 	fmt.Println(strings.Join(connector.Enabled(), ", "))
 }