Add Backend Service

[j-toscani]

Description (five sentences max.) We will need a Websocket-Server to handle player connections. As Next cannot handle this, we need a custom server.

Possible implementation Split the project into two packages and add a bun and TS compatible Backend Framework.

Acceptance Criteria

• The Project has two packages: Frontend and Backend
• The Frontend folder contains all the Next-Code
• The Backend Folder contains a startable Server with a "Hello World" GET-Route
• The Backend promises a simple and performant Websocket implementation

Out of Scope

• additional routes
• Websocket implementation

Document optional improvements Optional. Could lead to a better feature.