feat(chat): support hidden chat buffers on creation

[bassamsdata]

Description

This PR introduces a small feature enhancement to support opening chat buffers programmatically in a hidden (background) state.

Currently, achieving this requires a workaround: opening the chat visibly, then immediately hiding it and restoring the previously active chat (if any). This change removes the need for that hack by adding native support for hidden chat buffers.

Note:
This modification is minimal and does not affect any existing behavior. It only applies to programmatic use cases, such as when creating chats via chat:new() with the hidden = true option enabled.

Use cases:
Allows creating and managing chat buffers programmatically in the background without interrupting the user's current context. This enables automation, preloading, or preparation of chats that are only shown when needed. I'm building a feature that relies on this behavior.

Thank you

AI Usage

None.

Related Issue(s)

None, this is a feature request.

Screenshots

Checklist

• I've read the contributing guidelines and have adhered to them in this PR
• I confirm that this PR has been majority created by me, and not AI (unless stated in the "AI Usage" section above)
• I've run make all to ensure docs are generated, tests pass and StyLua has formatted the code
• (optional) I've added test coverage for this fix/feature
• (optional) I've updated the README and/or relevant docs pages