* add annotate to Gemfile

* rails g annotate:install

* configure annotate_models

* add schema info to models

* fix rubocop to add frozen_string_literal

* Detect extension for preview card

* next

* OEmbed support for PreviewCard

* Improve ProviderDiscovery code failure treatment

* Do not crawl links if there is a content warning, since those
don't display a link card anyway

* Reset db schema

* Fresh migrate

* Fix rubocop style issues
Fix #1681 - return existing access token when applicable instead of creating new

* Fix test

* Extract http client to helper

* Improve oembed controller