fix(use-roadiz-page-title): siteName query

[willybrauner]

Initially, if the first query commonContent.data.value?.head?.siteName return undefined, we tried to get the siteName via useRuntimeConfig().public.site.name which occur this error:

ℹ Error: [nuxt] A composable that requires access to the Nuxt instance was called outside of a plugin, Nuxt hook, Nuxt middleware, or Vue setup function. This is probably not a Nuxt bug. Find out more at https://nuxt.com/docs/4.x/guide/concepts/auto-imports#vue-and-nuxt-composables.

Composables like useRuntimeConfig() require access to the Nuxt app instance, which is only available during the synchronous execution of a Vue setup() function, not in a computed, that is "Lazy". (For more information about the lazy evaluation of the computed function: https://willybrauner.com/journal/signal-the-push-pull-based-algorithm ;))

So we just have to declare useRuntimeConfig outside the computed.