Add “Update available” navigation item at top of navbar when new Mastodon versions are available (#39705)

config/locales/en.yml

@@ -1226,6 +1226,7 @@ en:
           other: Used by %{count} people over the last week
       title: Recommendations & Trends
       trending: Trending
+    update_available: Update available
     username_blocks:
       add_new: Add new
       block_registrations: Block registrations

config/navigation.rb

@@ -7,10 +7,12 @@ SimpleNavigation::Configuration.run do |navigation|
     n.item :web, safe_join([material_symbol('chevron_left'), t('settings.back')]), root_path
 
     n.item :software_updates,
-           safe_join([material_symbol('report'), t('admin.critical_update_pending')]),
+           safe_join(
+             SoftwareUpdate.urgent_pending? ? [material_symbol('report'), t('admin.critical_update_pending')] : [material_symbol('system_update_alt'), t('admin.update_available')]
+           ),
            admin_software_updates_path,
-           if: -> { Rails.configuration.x.mastodon.software_update_url.present? && current_user.can?(:view_devops) && SoftwareUpdate.urgent_pending? },
-           html: { class: 'warning' }
+           html: { class: SoftwareUpdate.urgent_pending? ? 'warning' : nil },
+           if: -> { Rails.configuration.x.mastodon.software_update_url.present? && current_user.can?(:view_devops) && SoftwareUpdate.pending? }
 
     n.item :profile, safe_join([material_symbol('person'), t('settings.profile')]), settings_profile_path, if: -> { current_user.functional? && !self_destruct }, highlights_on: %r{/settings/profile|/settings/featured_tags|/settings/verification}
     n.item :privacy, safe_join([material_symbol('globe'), t('privacy.title')]), settings_privacy_path, if: -> { current_user.functional? && !self_destruct }, highlights_on: %r{/settings/privacy}