fix(nuxt): opt renderer route out of i18n localization

[sandros94]

Resolves #171

As per issue description, with @nuxtjs/i18n and strategy: 'prefix', i18n localises every page route and removes the unprefixed originals. The renderer placeholder page had no opt-out, so /__compodium__/renderer simply stopped existing: the request 404s (with X-Frame-Options: DENY) and the devtools preview iframe stays blank, which makes it look like a rendering bug instead of a routing one.

The fix is basically a one-liner: the placeholder route is now registered with meta: { i18n: false }, which i18n treats as its highest-precedence route-level opt-out (it wins over defineI18nRoute() and the pages config). No module detection needed, without i18n the meta key is just a no-op.

Also added an i18n fixture + test asserting the renderer responds on the unprefixed path with strategy: 'prefix' — that's the exact case that had no coverage. Verified it 404s without the fix and passes with it. Other strategies (prefix_except_default, no_prefix) keep an unprefixed default route so they were never affected.

Development note: @nuxtjs/i18n is only added as a devDependency of @compodium/nuxt for the fixture, nothing ships to consumers

I couldn't reproduce this issue vue side with vue-i18n, but I'm not that good on that so I prefer to limit my changes on nuxt

[sandros94]

This should also theoretically work with nuxt-i18n-micro. But if it doesn't I would honestly prefer to add meta: { i18n: false } support there instead of adding a branch here

EDIT: spaned a fable to doublecheck this, no it does not support meta: { i18n: false } but it already ignores routes that are tagged as internal paths, so no changes needed for that module

[sandros94]

Pushed two more fixes after field-testing this in the wild:

1. the placeholder route also needs a name: i18n's localization middleware treats nameless routes as localizable and redirects /__compodium__/renderer to a prefixed variant that was never generated
2. hookOnce('pages:extend') → hook with an idempotent push: pages:extend re-runs on every pages rebuild, so adding/removing any page file mid-session silently dropped the placeholder until a dev server restart

EDIT: also noticed that ts v7 is not working, because compodium is using v5.x api, but this is a different topic