Add initial Go CLI skeleton

internal/cli/inbox/root.go

@@ -0,0 +1,28 @@
+package inbox
+
+import (
+	"github.com/spf13/cobra"
+)
+
+type rootOptions struct {
+	dbPath string
+	json   bool
+	agent  string
+}
+
+func NewRootCmd() *cobra.Command {
+	opts := &rootOptions{}
+
+	cmd := &cobra.Command{
+		Use:   "inbox",
+		Short: "Worker-facing durable coordination bus",
+	}
+
+	cmd.PersistentFlags().StringVar(&opts.dbPath, "db", ".agents/coord.db", "SQLite database path")
+	cmd.PersistentFlags().BoolVar(&opts.json, "json", false, "Emit machine-readable JSON")
+	cmd.PersistentFlags().StringVar(&opts.agent, "agent", "", "Agent identity")
+
+	cmd.AddCommand(newInitCmd(opts))
+
+	return cmd
+}