feat: bundle Terebi Sunset as a selectable local theme

main.go

@@ -192,6 +192,11 @@ func validatePair(pair currentPair, stderr io.Writer) error {
 func validateTheme(theme string, stderr io.Writer) error {
 	cmd := exec.Command("tinty", "info", theme)
 	cmd.Stdout = io.Discard
+	if err := cmd.Run(); err == nil {
+		return nil
+	}
+	cmd = exec.Command("tinty", "info", theme, "--custom-schemes")
+	cmd.Stdout = io.Discard
 	cmd.Stderr = stderr
 	return cmd.Run()
 }