ConfigCat SDK for JavaScript SSR

The `configcat-js-ssr` package provides an official ConfigCat SDK for integrating feature flags into Server-Side Rendered (SSR) JavaScript applications, such as those built with Nuxt.js or Vue.js. It allows developers to manage feature toggles remotely via the ConfigCat Dashboard, enabling the separation of releases from deployments and targeting specific user groups. Currently at version 8.5.3, this SDK is in maintenance mode, superseded by the unified ConfigCat SDK for JavaScript. It receives only critical security patches, with official support ending on August 31, 2026. Developers are strongly encouraged to migrate to the new unified SDK, which offers a consolidated experience for both browser and Node.js environments and removes the need for a separate SSR-specific SDK. Its key differentiator was its specialized focus on SSR environments, but this has been absorbed by the unified SDK.