Fix being able to spoof link verification (#20217)

- Change verification to happen in `default` queue
- Change verification worker to only be queued if there's something to do
- Add `link` tags from metadata fields to page header of profiles

app/models/account/field.rb

@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+class Account::Field < ActiveModelSerializers::Model
+  MAX_CHARACTERS_LOCAL  = 255
+  MAX_CHARACTERS_COMPAT = 2_047
+
+  attributes :name, :value, :verified_at, :account
+
+  def initialize(account, attributes)
+    # Keeping this as reference allows us to update the field on the account
+    # from methods in this class, so that changes can be saved.
+    @original_field = attributes
+    @account        = account
+
+    super(
+      name:        sanitize(attributes['name']),
+      value:       sanitize(attributes['value']),
+      verified_at: attributes['verified_at']&.to_datetime,
+    )
+  end
+
+  def verified?
+    verified_at.present?
+  end
+
+  def value_for_verification
+    @value_for_verification ||= begin
+      if account.local?
+        value
+      else
+        extract_url_from_html
+      end
+    end
+  end
+
+  def verifiable?
+    value_for_verification.present? && /\A#{FetchLinkCardService::URL_PATTERN}\z/.match?(value_for_verification)
+  end
+
+  def requires_verification?
+    !verified? && verifiable?
+  end
+
+  def mark_verified!
+    @original_field['verified_at'] = self.verified_at = Time.now.utc
+  end
+
+  def to_h
+    { name: name, value: value, verified_at: verified_at }
+  end
+
+  private
+
+  def sanitize(str)
+    str.strip[0, character_limit]
+  end
+
+  def character_limit
+    account.local? ? MAX_CHARACTERS_LOCAL : MAX_CHARACTERS_COMPAT
+  end
+
+  def extract_url_from_html
+    doc = Nokogiri::HTML(value).at_xpath('//body')
+
+    return if doc.children.size > 1
+
+    element = doc.children.first
+
+    return if element.name != 'a' || element['href'] != element.text
+
+    element['href']
+  end
+end