fix: escape literals in scan diff

[kriswest]

resolves #1238

Escapes string literals in scanDiff using the escape-string-regexp library, which has been adopted into es2025 to implement RegExp.escape(). RegExp.escape() is not yet supported in TypeScript and requires at least node24 or chromium 138, hence, I've gone with the dependency for now and left a note to replace it when we move to requiring node24.

Adjusted the relevant test to include regex syntax so that it will fail if not correctly escaped.

[netlify]

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[kriswest]

@coopernetes assigned you for review as you mentioned needing to use this soon. Literals in commit messages are handled differently (as per the issue) (case insensitve substring match, as opposed to case insensitive regex match)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.40%. Comparing base (13ee734) to head (675a692).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1251   +/-   ##
=======================================
  Coverage   83.39%   83.40%           
=======================================
  Files          70       70           
  Lines        3006     3007    +1     
  Branches      501      501           
=======================================
+ Hits         2507     2508    +1     
  Misses        396      396           
  Partials      103      103           

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[coopernetes]

LGTM 👍