test(integration): fix Nuxt 3.16 bundle-stats snapshots

Coerce null asset gzipSize before matching so Bun snapshot matchers
(expect.any(Number)) work. Refresh Nuxt generate-bundle-stats snapshots
after the Nuxt ~3.16 upgrade; use Any<String> for bundler/plugin versions.

Made-with: Cursor

Author: thomasrockhu-codecov