fix: use u200B instead of uF800

[Asraye]

Swaps to u200B instead of uF800 for sanitization. uF800 isn't rendered by the majority of browsers and can cause some rendering weirdness when used (e.g. showing up as a glyph). This PR switches it to u200B, which is the more commonly used zero-width character and is generally handled cleanly without any rendering issues.

How was this PR tested?

Tested all other markdowns to make sure formatting isn't broken, and remains as expected.

Screenshots & Screencasts (if appropriate)

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Checklist:

• I have carefully read the contributing guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if applicable
• I have no unrelated changes in the PR
• I have confirmed that any new dependencies are strictly necessary
• I have written tests for new code (if applicable)
• I have followed naming conventions/patterns in the surrounding code

Please declare, if any, LLM usage involved in creating this PR

None
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