rtmp-services: Add Stream24

[joshuaissa390-eng]

Description

Adds Stream24 to the RTMP services list. Stream24 is a professional
multistreaming SaaS platform that enables simultaneous live broadcasting
to YouTube, Facebook, Twitch, TikTok, Instagram, X (Twitter), LinkedIn,
and more from a single RTMP ingest.

• Ingest URL: rtmp://app.stream24.io/live
• Stream key: personal key from user dashboard at app.stream24.io
• Documentation: https://stream24.io/support

I am the founder and operator of Stream24. This submission is made on
behalf of the service.

Motivation and Context

OBS users currently have to select "Custom" and manually enter the
Stream24 RTMP URL. Adding Stream24 to the services list removes that
friction and auto-fills the server URL for users.

How Has This Been Tested?

• RTMP ingest URL tested with OBS Studio on macOS and Windows
• Stream key authentication verified against live platform
• services.json validated at jsonlint.com — valid JSON confirmed
• package.json version incremented from 285 to 286

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• I have read the contributing document.
• My code follows the project's style guidelines
• My code is not on the master branch.
• My code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.