test: marked.test.ts asserts exact HTML output instead of semantic behavior

[SHUBHANSHU602]

marked.test.ts asserts full HTML strings using toEqual, including whitespace and formatting:

Problem:

HTML output from marked + highlight.js is not a stable API
Minor dependency upgrades can change formatting without breaking functionality
Tests fail on representation differences rather than logical regressions

File:-src/helpers/tests/marked.test.ts

[AceTheCreator]

Please don't open issues that re not necessary for the sake of GSoC, please refrain from doing that.