feat(01-03): add deterministic rich CLI output

- Inject bonfire.Output from stdin/stdout/stderr with stdlib widgets and x/term
- Degrade spinner, progress, table and prompts without a TTY or color
- Reject plugin command names that are not namespace:verb

examples/hello/main.go

@@ -37,7 +37,10 @@ func run(args []string, out io.Writer) error {
 			commands = append(commands, hasCommands.Commands()...)
 		}
 	}
-	root := bonfire.NewRoot("hello", commands, out)
+	root, err := bonfire.NewRoot("hello", commands, out)
+	if err != nil {
+		return err
+	}
 	root.SetArgs(args)
 	return root.Execute()
 }