Add per-node translation management: list, edit, destroy, compare

Replaces the old locale-switch-and-edit-the-same-screen workflow,
which conflated presentation locale with content locale and let an
editor silently drift into editing the wrong language with no
persistent signal that anything had changed. Non-default-locale
content now has its own explicit routes and screens, never sharing
a route param with the ambient chrome locale.

- PageTranslationsController: index/show/edit/update/destroy,
  scoped to Page.non_default_locales; update handles first-time
  creation too, so there's no separate new/create step.
- Reads go through the actual PageTranslation row
  (Page#translation_summary), never through the Globalize
  fallback-bearing accessor -- fallback is correct for public
  rendering but wrong for editing, where a missing translation
  needs to look empty, not borrowed from another locale.
- Translations ride on the page's own draft/head cycle; no
  independent publish state.
- nodes#show gains a Translations section (per-locale Lock+Edit /
  Create+Lock, Destroy, a link into the read-only Compare view) and
  a locale indicator on its own default-locale content; nodes#edit,
  nodes#update, and nodes#autosave are pinned to the default locale
  via Globalize.with_locale regardless of the ambient route locale.
- nodes#show no longer double-loads the node or calls wipe_draft!
  on every view (see previous commit for why that's now safe).
- .preview_link_row is renamed .aligned_action_row now that it has
  a second real consumer.

1 files changed, 21 insertions, 0 deletions

diff --git a/app/models/page.rb b/app/models/page.rb
index db5b688..f796228 100644
--- a/app/models/page.rb
+++ b/app/models/page.rb
@@ -87,6 +87,27 @@ class Page < ApplicationRecord
     end
   end
 
+  def self.non_default_locales
+    I18n.available_locales - [:root, I18n.default_locale]
+  end
+
+  # One row per non-default locale, read from the actual translation
+  # row -- never through the locale-dependent accessor, so a locale
+  # with no real translation yet reports as absent rather than quietly
+  # showing a fallback value borrowed from another locale.
+  def translation_summary
+    Page.non_default_locales.map do |locale|
+      translation = translations.find_by(:locale => locale)
+      {
+        :locale     => locale,
+        :exists     => translation.present?,
+        :title      => translation&.title,
+        :updated_at => translation&.updated_at,
+        :outdated   => translation.present? && outdated_translations?(:locale => locale)
+      }
+    end
+  end
+
   def self.untranslated(options = {:locale => :de})
     PageTranslation.all.group_by(&:page_id).select do |k,v|
       v.size == 1 && v.map{|x| x.locale}.include?(options[:locale])