feat: Enable command prefix matching for all gt subcommands

Allows shorthand like 'gt ref at' for 'gt refinery attach'.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/root.go

@@ -33,6 +33,9 @@ func Execute() {
 }
 
 func init() {
+	// Enable prefix matching for subcommands (e.g., "gt ref at" -> "gt refinery attach")
+	cobra.EnablePrefixMatching = true
+
 	// Global flags can be added here
 	// rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file")
 }