fix(cmd): handle errors and improve output formatting

* update error handling in various commands to use blank identifier
* enhance output formatting for better readability
* add golangci-lint to Makefile for linting checks

cmd/pgtidy/main.go

@@ -29,20 +29,20 @@ func run(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	case "config":
 		return cmdConfig(args[1:], stdin, stdout, stderr)
 	case "version", "--version", "-v":
-		fmt.Fprintf(stdout, "pgtidy %s\n", version)
+		_, _ = fmt.Fprintf(stdout, "pgtidy %s\n", version)
 		return 0
 	case "help", "-h", "--help":
 		usage(stdout)
 		return 0
 	default:
-		fmt.Fprintf(stderr, "pgtidy: unknown command %q\n", args[0])
+		_, _ = fmt.Fprintf(stderr, "pgtidy: unknown command %q\n", args[0])
 		usage(stderr)
 		return 2
 	}
 }
 
 func usage(w io.Writer) {
-	fmt.Fprint(w, `pgtidy — PostgreSQL formatter and linter
+	_, _ = fmt.Fprint(w, `pgtidy — PostgreSQL formatter and linter
 
 Usage:
   pgtidy fmt    [flags] [files...]  Format SQL/PL-pgSQL (stdin if no files)