Add top-level mcp edit command

Shortcut for mcp service edit — opens the service definition in $EDITOR.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/mcp/edit.go

@@ -0,0 +1,12 @@
+package main
+
+import "github.com/spf13/cobra"
+
+func editCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "edit <service>",
+		Short: "Open service definition in $EDITOR",
+		Args:  cobra.ExactArgs(1),
+		RunE:  runServiceEdit,
+	}
+}