Add raum.app + flag two closed platforms (MeetinVR, Horizon Workrooms) #8

Hi Seckin,

Two platforms in the Collaboration section have shut down:

• MeetinVR — closed April 30, 2026
• Horizon Workrooms — closed February 2026

Worth flagging for removal or marking as discontinued.

Suggested addition: raum.app — Fully-immersive VR meeting platform for professional teams. Persistent virtual offices and structured meeting environments, enterprise-focused.

Proposed entry:
raum.app - Fully-immersive VR meeting platform for professional teams

Happy to open a PR if you'd prefer that workflow.

Thanks for maintaining this list — it's a great resource.