Fix markdown table selection alignment

[ShrootBuck]

Self-Review Checklist:

• I've reviewed my own diff for quality, security, and reliability
• Unsafe blocks (if any) have justifying comments
• The content is consistent with the UI/UX checklist
• Tests cover the new/changed behavior
• Performance impact has been considered and is acceptable

Fixes markdown selection and copy hit areas for center- and right-aligned table text.

Rendered markdown lines now keep their alignment, and source-position hit testing plus selection highlight bounds apply the same per-row alignment offset as the painted text. This keeps selectable/copyable table text aligned with what users see without changing the underlying copied Markdown. There are before and after videos below that probably make more sense than what I wrote above.

Before:

before.mov

After:

after.mov

Release Notes:

• Fixed markdown table text selection/copy alignment for centered and right-aligned cells.

[RemcoSmitsDev]

Hey not sure if you know but there is already a PR up for this. Duplicate of: #57283

[ShrootBuck]

oh, thanks for letting me know!