Migration to Next v14

[qhantom]

DESCRIPTION

This PR updates Next.js to latest major version 14 along with all dependent i18next packages.

TO-DO

• [x] implement and update tests
• [x] update docs
• [x] pull main & resolve merge conflicts
• [x] check Vercel deployment

CLOSES

Closes #483

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
app	✅ Ready (Inspect)	Visit Preview	Apr 24, 2024 1:35pm
docs	✅ Ready (Inspect)	Visit Preview	Apr 24, 2024 1:35pm

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