Add public API support for pinning and unpinning chat messages

[GavenDay]

Is your feature request related to a problem? Please describe.

External bots and integrations can post messages to Kick chat, but there is currently no documented public API action for pinning or unpinning those messages.

This limits moderation and automation use cases where an authorized bot needs to temporarily highlight a message, such as announcements, sponsored messages, giveaways, alerts, or other streamer-approved content.

The functionality already exists within Kick chat for streamers and moderators, but external integrations do not have a supported way to trigger the same moderation action.

Describe the solution you'd like

Add public API endpoints that allow an authorized application to pin and unpin chat messages.

For example:

POST /public/v1/chat/pinned-message

{
  "broadcaster_user_id": "...",
  "message_id": "..."
}