Update dependencies and add gofumpt Makefile target

Bump cc-backend to v1.5.4 and cc-lib to v2.12.0 with transitive
dependency updates, add a `make fmt` target running gofumpt, ignore
the dist directory, and reformat multi-line calls to gofumpt style.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Entire-Checkpoint: 09016e793f9b

cmd/cc-metric-store/main.go

@@ -177,7 +177,8 @@ func run() error {
 		}
 		cclog.Infof("Cleaning up checkpoints older than %s...", from.Format(time.RFC3339))
 		n, err := metricstore.CleanupCheckpoints(
-			metricstore.Keys.Checkpoints.RootDir, cleanupDir, from.Unix(), deleteMode)
+			metricstore.Keys.Checkpoints.RootDir, cleanupDir, from.Unix(), deleteMode,
+		)
 		if err != nil {
 			return fmt.Errorf("checkpoint cleanup: %w", err)
 		}

cmd/cc-metric-store/server.go

@@ -49,7 +49,8 @@ func (s *Server) init() error {
 	if flagDev {
 		cclog.Print("Enable Swagger UI!")
 		s.router.HandleFunc("GET /swagger/", httpSwagger.Handler(
-			httpSwagger.URL("http://"+config.Keys.Address+"/swagger/doc.json")))
+			httpSwagger.URL("http://"+config.Keys.Address+"/swagger/doc.json"),
+		))
 	}
 
 	return nil
@@ -81,7 +82,8 @@ func (s *Server) Start(ctx context.Context) error {
 
 	if config.Keys.CertFile != "" && config.Keys.KeyFile != "" {
 		cert, err := tls.LoadX509KeyPair(
-			config.Keys.CertFile, config.Keys.KeyFile)
+			config.Keys.CertFile, config.Keys.KeyFile,
+		)
 		if err != nil {
 			return fmt.Errorf("loading X509 keypair (check 'https-cert-file' and 'https-key-file' in config.json): %w", err)
 		}