Add partial MSC4459 support and refactor related code

[dozro]

Description

partial implementation of MSC4459

Currently only sending the data and not rendering anything

Fixes #729

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

AI disclosure:

No AI used

[github-actions]

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Status	Preview URL	Commit	Alias	Updated (UTC)
✅ Deployment successful!	https://pr-730-sable.raspy-dream-bb1d.workers.dev	f49e84d	pr-730	Mon, 04 May 2026 04:59:16 GMT