* Fix structured data parsing from links choking on bad data

- Fix og:url meta tag being prioritized over canonical link tag
- Fix structured data parsing choking on commented-out CDATA declarations
- Fix HTML entities in title, description, provider_name, author_name
- Change structured data parsing to attempt every JSON-LD script tag

* Remove unnecessary slash escapes from CDATA regex pattern

* Refactor tests

* Add tests

* Fix replies collection incorrectly looping

* Add tests

* Fix instance actor not being dereferenceable

* Fix tests

* Fix tests for real

Fixes #17382

Note that unconfirmed and unapproved accounts can still be searched for
and their (empty) account retrieved using the REST API.

* Change account and user fabricators to simplify and improve tests

- `Fabricate(:account)` implicitly fabricates an associated `user` if
  no `domain` attribute is given (an account with `domain: nil` is
  considered a local account, but no user record was created), unless
  `user: nil` is passed
- `Fabricate(:account, user: Fabricate(:user))` should still be possible
  but is discouraged.

* Fix and refactor tests

- avoid passing unneeded attributes to `Fabricate(:user)` or
  `Fabricate(:account)`
- avoid embedding `Fabricate(:user)` into a `Fabricate(:account)` or the other
  way around
- prefer `Fabricate(:user, account_attributes: …)` to
  `Fabricate(:user, account: Fabricate(:account, …)`
- also, some tests were using remote accounts with local user records, which is
  not representative of production code.

Fix #17344

* Fix error-prone SQL queries in Account search

While this code seems to not present an actual vulnerability, one could
easily be introduced by mistake due to how the query is built.

This PR parameterises the `to_tsquery` input to make the query more robust.

* Harden code for Status#tagged_with_all and Status#tagged_with_none

Those two scopes aren't used in a way that could be vulnerable to an SQL
injection, but keeping them unchanged might be a hazard.

* Remove unneeded spaces surrounding tsquery term

* Please CodeClimate

* Move advanced_search_for SQL template to its own function

This avoids one level of indentation while making clearer that the SQL template
isn't build from all the dynamic parameters of advanced_search_for.

* Add tests covering tagged_with, tagged_with_all and tagged_with_none

* Rewrite tagged_with_none to avoid multiple joins and make it more robust

* Remove obsolete brakeman warnings

* Revert "Remove unneeded spaces surrounding tsquery term"

The two queries are not strictly equivalent.

This reverts commit 86f16c537e06c6ba4a8b250f25dcce9f049023ff.

* Add support for editing for published statuses

* Fix references to stripped-out code

* Various fixes and improvements

* Further fixes and improvements

* Fix updates being potentially sent to unauthorized recipients

* Various fixes and improvements

* Fix wrong words in test

* Fix notifying accounts that were tagged but were not in the audience

* Fix mistake

* Add support for private pinned toots

* Allow local user to pin private toots

* Change wording to avoid "direct message"

* Add admin option to remove canonical email blocks from a deleted account

* Add tootctl canonical_email_blocks to inspect and remove canonical email blocks

* Add ability to purge undeliverable domains from admin interface

* Add tests

* Fix #16937

* Add test for statuses order

* Add trending links

* Add overriding specific links trendability

* Add link type to preview cards and only trend articles

Change trends review notifications from being sent every 5 minutes to being sent every 2 hours

Change threshold from 5 unique accounts to 15 unique accounts

* Fix tests

* Fix error when suspending user with an already-existing canonical email block

Fixes #17033

While attempting to create a `CanonicalEmailBlock` with an existing hash would
raise an `ActiveRecord::RecordNotUnique` error, this being done within a
transaction would cancel the whole transaction. For this reason, checking for
uniqueness in Rails would query the database within the transaction and avoid
invalidating the whole transaction for this reason.

A race condition is still possible, where multiple accounts sharing a canonical
email would be blocked in concurrent transactions, in which only one would
succeed, but that is way less likely to happen that the current issue, and can
always be retried after the first failure, unlike the current situation.

* Add tests

Save preview cards under their canonical URL

Increase max redirects to follow from 2 to 3

Broken since #15827

* Add tests

* Fix some link previews being incorrectly generated from different prior links

PR #12403 added a cache to avoid redundant queries when the OEmbed endpoint can
be guessed from the URL. This caching mechanism is not perfectly correct as
there is no guarantee that all pages from a given domain share the same
OEmbed provider endpoint.

This PR prevents the FetchOEmbedService from caching OEmbed endpoint that
cannot be generalized by replacing a fully-qualified URL from the endpoint's
parameters, greatly reducing the number of incorrect cached generalizations.

* Add support for fetching Create and Announce activities by URI

This should improve compatibility with ZAP and offer a way to fetch boosts,
which is currently not possible.

* Add tests

* Add followed_by? to account_interactions

* Add RemoveFromFollowersService

* Fix AccountBatch to use RemoveFromFollowersService

* Add remove from followers API

* Allow keeping 1 boosts/favs on auto deleting posts

* Fix tests

* Add tests

* Fix scheduled statuses decreasing statuses counts

Fixes #16774

* Add tests

* Fix error when rendering public pages with media attachments

* Add tests

* Fix tests

* Please CodeClimate

* Fix media attachment size validation not correctly accounting for file type

Fixes a regression introduced in #16724 caused by the fact that kt-paperclip
now correctly runs validations before processing, meaning that file size
verification could not rely on our before_post_processing hook.

Moved the `before_post_processing` hooks to `before_validate` to make sure
the media attachment type is set correctly before the file gets validated.

* Add tests

* Add tests

* Fix webauthn secure key authentication

Fixes #16769

* Switch from unmaintained paperclip to kt-paperclip

* Drop some compatibility monkey-patches not required by kt-paperclip

* Drop media spoof check monkey-patching

It's broken with kt-paperclip and hopefully it won't be needed anymore

* Fix regression introduced by paperclip 6.1.0

* Do not rely on pathname to call FastImage

* Add test for ogg vorbis file with cover art

* Add audio/vorbis to the accepted content-types

This seems erroneous as this would be the content-type for a vorbis stream
without an ogg container, but that's what the `marcel` gem outputs, so…

* Restore missing for_as_default method

* Refactor Attachmentable concern and delay Paperclip's content-type spoof check

Check for content-type spoofing *after* setting the extension ourselves, this
fixes a regression with kt-paperclip's validations being more strict than
paperclip 6.0.0 and rejecting some Pleroma uploads because of unknown
extensions.

* Please CodeClimate

* Add audio/vorbis to the unreliable set

It doesn't correspond to a file format and thus has no extension associated.

Follow-up to #16510, forgot the controller exposing the actual followers…

* Stop setting a shortcode to newly-created media attachments

The WebUI has stopped using the “short media URL” in ages. This isn't used
anywhere except for mail notifications.

Deprecating it would allow us to eventually get rid of at least a database
column and corruption-prone index, as well as a controller.

* Fix tests

Fixes #16699

Fixes #16602

* Add tests

* Add security-related tests

My first (unpublished) attempt at fixing the issues introduced (extremely
hard-to-exploit) security vulnerabilities, addressing them in a test.

* Fix authentication failures after going halfway through a sign-in attempt

* Refactor `authenticate_with_sign_in_token` and `authenticate_with_two_factor` to make the two authentication steps more obvious

* Add tests for SuspendAccountService

* Add tests for UnsuspendAccountService

* Fix followers synchronization mechanism not working when URI has empty path

To my knowledge, there is no current implementation on the fediverse
that can use bare domains (e.g., actor is at https://example.org instead of
something like https://example.org/actor) that also plans to support the
followers synchronization mechanism. However, Mastodon's current implementation
would exclude such accounts from followers list.

Also adds tests and rename them to reflect the proper method names.

* Move url prefix regexp to its own constant