Fix local resource previews for paths containing hashes

[bodhibuurstede-sys]

Summary

• Encode local filesystem paths when building file:// URLs so # characters stay part of the pathname instead of becoming URL fragments.
• Add ResourcesLoader coverage for a Weekend Jam #1-style path and cache-busting query strings.
• Make the pre-built libGD.js downloader try matching master/commit/<hash> builds before master/latest, so detached PR CI does not pick an incompatible generated file.

Fixes #4015.

Testing

• Ran a Node URL parsing check for paths containing # and cache-busting query parameters.
• Semaphore Fast tests (not building GDevelop.js - can have false negatives): passed on the latest commit.
• Not run locally: full Jest suite, because this Codex environment does not have the repository dependency setup needed for the full GDevelop test suite.

[bodhibuurstede-sys]

Hi @4ian, the Semaphore PR check is green now after the libGD.js fallback update. This should be ready for review when you have a chance; happy to adjust anything.