Chatroom: Add `socket.io` and `socket.io-client`

[fhelfer]

This PR adds socket.io and socket.io-client as NPM dependency for the chatroom.

General Information:

• [X] this dependency was already used in ILIAS.
• [X] License: MIT

Usages:

• components/ILIAS/Chatroom/chat/api.js
• components/ILIAS/Chatroom/chat/Bootstrap/SetupServer.js

Wrapped By:

• il.Chatroom (see: components/ILIAS/OnScreenChat/js/chat.js)
• SetupServer see:
  • components/ILIAS/Chatroom/chat/Bootstrap/SetupServer.js

Reasoning:

socket.io is a library that enables low-latency, bidirectional and event-based communication between a client and a server. It is used in the Node.js based ILIAS chat server, which relies on the provided WebSocket low-level transport mechanisms. Socket.IO offers HTTP long-polling as a fallback option, which is useful in environments that don't support WebSockets.

Maintenance:

socket.io is a well-maintained package with major releases every few years and recent activities. (The latest version is from 25.10.2025)

Links:

• NPM: https://www.npmjs.com/package/socket.io / https://www.npmjs.com/package/socket.io-client
• GitHub: https://github.com/socketio/socket.io (they are maintained in the same repo)
• Documentation: https://socket.io/docs/

[matthiaskunkel]

Jour Fixe, 08 DEC 2025: Dependency is accepted for ILIAS 12.