Preserve noprotect when changing the p5.js library version

[dyk1454683243-sudo]

Issue:

Fixes #4303

Changing the p5.js library version in Preferences rewrites index.html through documentElement.outerHTML. That serialization drops comments outside <html>, including a leading <!-- noprotect -->, so Loop Protection Off flips back to On. The same rewrite path is used by addon toggles.

Demo:

No visual UI change. Loop Protection Off (<!-- noprotect --> present) now survives a library version change; Loop Protection On still does not insert a noprotect comment.

Changes:

• Add preserveNoProtect() so HTML rewrites keep an existing noprotect comment and do not invent one.
• Use it in useP5Version serializeResult(), which replaceVersion and the addon setters already share.
• Preferences handleLoopProtection(true) still removes noprotect through toggleLoopProtection and is unchanged.
• Unit tests: with noprotect → replaceVersion keeps it; without → stays without; addon setters do not drop it.

This is a separate branch from #4309 / #4311.

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #4303
• meets the standards outlined in the accessibility guidelines

[dyk1454683243-sudo]

Withdrawing this PR while I clean up a high-volume open-PR backlog. Sorry for the noise — happy to come back later with a focused change if useful.