test: upgrade to Vitest 4

[erickzhao]

Pre-requisite for some of the Node 22 work in #4059 because of some import.meta.resolve implementation issues with Vitest that were fixed upstream.

This PR:

• Upgrades to Vitest 4 via yarn up.
• Upgrades the root workspace's version of Vite to 7 (to pick up import.meta.resolve fix). I needed to add an exception to the Yarn Constraints for the time being.
• Migrates vitest.workspace.mts to the projects key in vitest.config.mts.
• Updated PublisherS3.spec.ts to use vi.importActual, since applying vi.mock('node:fs') in Vitest 4 actually mocks out the fixture code too.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	vitest@​3.1.3 ⏵ 4.0.14	+1
	vite@​6.4.1 ⏵ 7.2.4	+3			-1

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[socket-security]

All alerts resolved. Learn more about Socket for GitHub.

This PR previously contained dependency changes with security issues that have been resolved, removed, or ignored.

Ignoring alerts on:

• [email protected]

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[erickzhao]

@SocketSecurity ignore npm/[email protected]

Looks like Vite/Vitest forked the old debug module:

vitest-dev/vitest#9057