Rename env vars to NUXT_PUBLIC_*

[MickL]

Currently the env vars are defined as:

ALGOLIA_API_KEY=""
ALGOLIA_APPLICATION_ID=""

• This is in contrast to all other variables that start with NUXT_ or NUXT_PUBLIC_, e.g. NUXT_SITE_ENV from nuxtjs/seo and NUXT_PUBLIC_I18N_BASE_URL from @nuxtjs/i18n
• They get removed in environments like Turbo Repo, if not prefixed with NUXT_ and not whitelisted
• They dont show that they get exposed to the public which is crucial if one might use a key that can edit and delete

Therefor I would suggest to rename them to:

ALGOLIA_API_KEY=""
ALGOLIA_APPLICATION_ID=""