fix: reload highlighter when language is available

[Soxasora]

Description

Fixes #2600
Adds the language dependency to the useEffect that dynamically loads the highlighter, triggering a reload of the highlighter once language is available.
Also memoizes the language computation and persists the loadHighlighter function across re-renders to avoid extra work.

Screenshots

Screen.Recording.2025-10-14.at.17.33.28.mp4

Additional Context

n/a

Checklist

Are your changes backward compatible? Please answer below:

For example, a change is not backward compatible if you removed a GraphQL field or dropped a database column.
Yes

On a scale of 1-10 how well and how have you QA'd this change and any features it might affect? Please answer below:
8, it works correctly on the given text.

For frontend changes: Tested on mobile, light and dark mode? Please answer below:
n/a

Did you introduce any new environment variables? If so, call them out explicitly here:
n/a

Did you use AI for this? If so, how much did it assist you?
No

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Note

Reloads the syntax highlighter when language becomes available/changes, memoizes language, and adds safe cleanup to avoid setting state after unmount.

• Code rendering (components/text.js > Code):
  • Memoizes language from className via useMemo and updates loadHighlighter dependency to [className].
  • Updates useEffect dependencies to [inline, language, loadHighlighter]; early-returns for inline and math.
  • Adds abort/cleanup guard to prevent state updates after unmount while loading highlighter.
  • Minor refactor: uses loaded Highlighter and sets theme once loaded.

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[adlai]

thank you @Soxasora for fixing and explaining the logic