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

cmd/summer/main_test.go

@@ -26,7 +26,10 @@ func TestToolCommandNames(t *testing.T) {
 	}
 
 	var buf bytes.Buffer
-	root := bonfire.NewRoot("summer", toolCommands(), &buf)
+	root, err := bonfire.NewRoot("summer", toolCommands(), &buf)
+	if err != nil {
+		t.Fatal(err)
+	}
 	root.SetArgs([]string{"make:plugin", "--help"})
 	if err := root.Execute(); err != nil {
 		t.Fatal(err)