Add light mode + toggle

[matr1x-hackmud]

Problem

Works towards #542

Context

Re-enables the default Docusaurus light / dark toggle and adds a hackmuddy light mode that does the following:

• Removes the scan-lines (not sure how we can make them work on a white background as-is)
• Puts a black text shadow around color tags to make sure the colors still stand out on a white background (may need some tweaking to make them prettier)

[matr1x-hackmud]

Some screenies:

(ignore the broken image i had spun down the test server lol)

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✅ matr1x-hackmud
❌ 1shira
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