Initial commit: unitdore scaffold + syncup/edit commands

- config: load/save/add unit, Unit struct
- runtime: podman + docker discovery and exists check
- cmd: syncup (discover + reconcile), edit, cobra root
- PLAN.md: full project plan

cmd/root.go

@@ -0,0 +1,31 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var configPath string
+
+var rootCmd = &cobra.Command{
+	Use:   "unitdore",
+	Short: "A door you open and close for container units",
+	Long: `Unitdore manages container units via systemd.
+
+It discovers running containers, stores them in a config file,
+and generates + manages systemd .service units for each one.`,
+	Version: "0.1.0",
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func init() {
+	rootCmd.PersistentFlags().StringVar(&configPath, "config", "/etc/unitdore/units.yaml", "path to units config file")
+}