feat: add optionsApi option to skip the Options API provider - #678

🔗 Linked issue

None. Related to #575, which added Options API support.

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

The plugin always installs @vue/apollo-option. Its global mixin runs on every component, even in apps that only use composables. In SSR its serverPrefetch hook makes every component render async, so useId() values get longer at each level:

reka-tabs-v-0-0-0-0-0-0-0-0-0-0-0-0-0-1-0-0-0-0-0-0-8-0-trigger-0   (now)
reka-tabs-v-0-19-1-trigger-0                                       (optionsApi: false)

This adds apollo.optionsApi. It defaults to true, so nothing changes for existing apps. Set it to false to skip the provider. Composables keep working. The apollo component option needs the provider, and without it this.$apollo is the plain { clients, defaultClient } object from useNuxtApp().$apollo, so this.$apollo.query() is gone.

I tried it on a Nuxt UI app with no Options API queries. With false, the HTML stays the same apart from the ids, pages are 2 to 5% smaller, and the server no longer runs @vue/apollo-option. CPU was mixed. One page got 13% faster, and a page with a big table got 6% slower, which I can't explain yet.

v5 has no tests, so the second commit adds vitest and @nuxt/test-utils, with tests for both settings and for the composables with optionsApi: false. Run pnpm dev:prepare, then pnpm test. I can drop that commit if you'd rather not have it.