Harden YouTube URL handling in embed feature

[dozro]

Description

This pull request refactors the parseYoutubeLink function in ClientPreview.tsx to use the standard URL API for parsing YouTube URLs. This change improves the reliability and maintainability of the code by handling edge cases and reducing manual string manipulation.

Improvements to YouTube URL parsing

• Refactored parseYoutubeLink to use the URL API for robust parsing of YouTube URLs, improving error handling and supporting more YouTube link formats.
• Enhanced extraction of video ID, playlist, and timestamp by using URL search parameters instead of manual string splitting, making the code more readable and less error-prone.

Fixes https://github.com/SableClient/Sable/security/code-scanning/9

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).

No AI involved

[7w1]

lgtm