Add standalone desktop workflow

internal/dialog/pickfolder_darwin.go

@@ -0,0 +1,20 @@
+package dialog
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+func PickFolder() (string, error) {
+	cmd := exec.Command("osascript", "-e", `POSIX path of (choose folder with prompt "Select a folder")`)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return "", fmt.Errorf("folder selection failed: %s", strings.TrimSpace(string(out)))
+	}
+	path := strings.TrimSpace(string(out))
+	if path == "" {
+		return "", fmt.Errorf("folder selection canceled")
+	}
+	return strings.TrimSuffix(path, "/"), nil
+}