Propper OpenGraph support for #/card/<id> pages

[Bottersnike]

At current the pages for cards provide just the default OpenGraph tags. This means that embed generators produce images like instead of as might be expected.

[Aixile]

Currently, Crypko is a pure single page application built on Vue, which means all meta tags in card pages are rendered by client-side javascript engines. However, most SNS crawlers won't execute javascript, so it is impossible to implement it for now. Moving to server-rendering requires refactoring the site with nuxt.js.

As an alternative solution, we provided a server-rendered link for users to share their Crypkos.