Fix various things in the directory (#9449)

* Fix missing variable in directory page title

* Order hashtags by number of people instead of alphabetically

* Add icon to OpenGraph preview of directory page

* Prevent line breaks in hashtags and ensure lowercase in the table

app/javascript/styles/mastodon/widgets.scss

@@ -300,6 +300,9 @@
       font-size: 18px;
       font-weight: 700;
       color: $primary-text-color;
+      white-space: nowrap;
+      overflow: hidden;
+      text-overflow: ellipsis;
 
       .fa {
         color: $darker-text-color;

app/models/tag.rb

@@ -20,7 +20,7 @@ class Tag < ApplicationRecord
 
   validates :name, presence: true, uniqueness: true, format: { with: /\A#{HASHTAG_NAME_RE}\z/i }
 
-  scope :discoverable, -> { joins(:account_tag_stat).where(AccountTagStat.arel_table[:accounts_count].gt(0)).where(account_tag_stats: { hidden: false }).order(name: :asc) }
+  scope :discoverable, -> { joins(:account_tag_stat).where(AccountTagStat.arel_table[:accounts_count].gt(0)).where(account_tag_stats: { hidden: false }).order('account_tag_stats.accounts_count desc') }
   scope :hidden, -> { where(account_tag_stats: { hidden: true }) }
 
   delegate :accounts_count,

app/views/directories/index.html.haml

 - content_for :page_title do
-  = t('directories.explore_mastodon')
+  = t('directories.explore_mastodon', title: site_title)
 
 - content_for :header_tags do
   %meta{ name: 'description', content: t('directories.explanation') }
 
-  = opengraph 'og:site_name', site_title
+  = opengraph 'og:site_name', t('about.hosted_on', domain: site_hostname)
+  = opengraph 'og:type', 'website'
   = opengraph 'og:title', t('directories.explore_mastodon', title: site_title)
   = opengraph 'og:description', t('directories.explanation')
+  = opengraph 'og:image', File.join(root_url, 'android-chrome-192x192.png')
 
 .page-header
   %h1= t('directories.explore_mastodon', title: site_title)
@@ -29,10 +31,10 @@
                 %td= account_link_to account
                 %td.accounts-table__count
                   = number_to_human account.statuses_count, strip_insignificant_zeros: true
-                  %small= t('accounts.posts', count: account.statuses_count)
+                  %small= t('accounts.posts', count: account.statuses_count).downcase
                 %td.accounts-table__count
                   = number_to_human account.followers_count, strip_insignificant_zeros: true
-                  %small= t('accounts.followers', count: account.followers_count)
+                  %small= t('accounts.followers', count: account.followers_count).downcase
                 %td.accounts-table__count
                   - if account.last_status_at.present?
                     %time.time-ago{ datetime: account.last_status_at.iso8601, title: l(account.last_status_at) }= l account.last_status_at