Bind the app port deliberately and document the proxy deployment (closes #268) (closes #226)

internal/server/routes.go

@@ -81,7 +81,7 @@ func (s *Server) setupGlobalMiddleware() {
 	// Sentry error reporting (if SENTRY_DSN is set). Repanic is
 	// true so panics still bubble up to the Recoverer middleware
 	// registered immediately above.
-	if s.sentryEnabled {
+	if s.sentryEnabled.Load() {
 		sentryHandler := sentryhttp.New(sentryhttp.Options{
 			Repanic: true,
 		})