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, 27 insertions, 0 deletions

diff --git a/app/views/page_translations/show.html.erb b/app/views/page_translations/show.html.erb
new file mode 100644
index 00000000..c5bd151f
--- /dev/null
+++ b/app/views/page_translations/show.html.erb
@@ -0,0 +1,27 @@
+<h1>Compare — <%= title_for_node(@node) %></h1>
+
+<div class="translation_compare">
+  <div class="translation_compare_column">
+    <h2><%= @locale.to_s.upcase %></h2>
+    <div class="node_description">Title</div>
+    <div class="node_content"><%= @translation&.title %></div>
+
+    <div class="node_description">Abstract</div>
+    <div class="node_content"><%= sanitize(@translation&.abstract.to_s) %></div>
+
+    <div class="node_description">Body</div>
+    <div class="node_content"><%= sanitize(@translation&.body.to_s) %></div>
+  </div>
+
+  <div class="translation_compare_column">
+    <h2><%= I18n.default_locale.to_s.upcase %> (default)</h2>
+    <div class="node_description">Title</div>
+    <div class="node_content"><%= @default_translation&.title %></div>
+
+    <div class="node_description">Abstract</div>
+    <div class="node_content"><%= sanitize(@default_translation&.abstract.to_s) %></div>
+
+    <div class="node_description">Body</div>
+    <div class="node_content"><%= sanitize(@default_translation&.body.to_s) %></div>
+  </div>
+</div>