Cleanup of some of the changes

[nushea]

Description

Fixes the issues with the sizing of the user-hero, small saving issue, previews now showing when put in the [](), and matrix.to links being added to link-previews even though they reasonably shouldn't. It also fixes the matrix.to links to be made with a trailing / to avoid weird tricks in the usage of them for malicious purposes

This is general maintenance however so does not really need a changeset because its just a bunch of extremely small changes

Fixes #740

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:

• Partially AI assisted (clarify which code was AI assisted and briefly explain what it does).
• Fully AI generated (explain what all the generated code does in moderate detail).

I had a nightmare that the new version shipped incomplete code