chore(deps): adopt vitest 4 (#834)

Dependabot bumped `@vitest/coverage-v8` to 4 on its own in several apps and
left `vitest` and `@vitest/ui` on 3. coverage-v8 4 peers vitest 4.1.11 exactly,
so a split trio cannot resolve at all: that is what took launchpad's npm ci
from green to red.

The three move together here, to 4.1.11, which is the current published version
of all of them.

Verified: npm install and the app's own test script both exit 0.

Author: rubenvdlinde