add GameStacker to community showcase

Author: riquenunes

website/docs/community/showcase/gamestacker.mdx

@@ -0,0 +1,19 @@
+---
+title: GameStacker
+description: A modern, console-like interface that unifies your game libraries.
+slug: /community/showcase/gamestacker
+image: /img/showcase/gamestacker.webp
+---
+
+<div className="text--center">
+  <img src="/img/showcase/gamestacker.webp" alt="GameStacker main dashboard" loading="lazy" />
+</div>
+
+[GameStacker](https://gamestacker.io) is a modern, elegant console-like interface that unifies your entire game collection into one beautiful dashboard.
+
+## Features
+
+- **Unified Library**: Automatically detects and imports games from external libraries (such as Steam, LaunchBox, and RetroBat), bringing your modern and retro collections into a single, cohesive interface.
+- **True Console Experience**: Built for controllers with responsive navigation, UI sound effects, and a dedicated in-game "Guide" overlay to control music and manage your session without alt-tabbing.
+- **Achievement Integration**: Tracks your progress across supported services, allowing you to view unlocks and Gamerscore directly from the dashboard.
+- **Multi-Profile Support**: Create unique profiles with custom avatars and specific color themes for a personalized experience.