Asset picker: attach/detach/reorder UI, read-only view, autosave fix

Replaces nodes#edit's old Images section -- a hidden panel dumping
every image asset in the system unfiltered (#image_browser) plus a
raw drag-and-drop box (#image_box) -- with a small search-and-click
picker built on the endpoint from the last two commits. Attaching
posts immediately and appends the new thumbnail via a cloned
<template> -- icons only render correctly through the Rails helper
server-side, so the template holds real, pre-rendered markup for JS
to clone rather than duplicating raw SVG in a JS string. Reordering is
jQuery UI sortable on the small attached list only, with a dedicated
drag handle rather than the whole thumbnail.

Two bugs caught while click-testing, fixed here rather than shipped
and patched after: the search panel never closed after attaching an
image, since the success handler re-triggered focus to keep it open
for attaching several in a row -- which meant it just re-populated
itself forever instead of signaling "done." Fixed to close explicitly;
a click-outside-closes handler was added alongside it, matching the
affordance the top-bar search already has.

A real, independent, pre-existing data bug surfaced during the same
testing: Node#autosave!'s first-time-creation branch never carried
related assets forward from whatever page was previously current --
attach an image, let autosave fire once, and it silently landed on a
fresh, assetless Page row. Long-dormant, not introduced by this work,
just finally exercised by something that made it visible. Fixed inside
the `unless self.autosave` guard specifically -- running this on every
call, not just creation, would overwrite anything attached directly to
an existing autosave in between, a worse bug than the one being fixed.

nodes#show gains a read-only Images section, rendered only when a page
actually has attached images, so an attachment can be confirmed
present without entering the edit/lock cycle -- useful on its own, and
specifically useful the next time an asset bug needs investigating.
Its thumbnail CSS is shared with the edit view's picker via a class
(.thumbnail_list) rather than duplicated under a second name.

1 files changed, 1 insertions, 0 deletions

diff --git a/app/views/layouts/admin.html.erb b/app/views/layouts/admin.html.erb
index 5ae363f..8bbc0d5 100644
--- a/app/views/layouts/admin.html.erb
+++ b/app/views/layouts/admin.html.erb
@@ -13,6 +13,7 @@
     <link rel="stylesheet" href="/stylesheets/admin.css">
     <script src="/javascripts/admin_search.js"></script>
     <script src="/javascripts/admin_interface.js"></script>
+    <script src="/javascripts/related_assets.js"></script>
     <script>
       var ADMIN_SEARCH_URL = "<%= admin_search_path %>";
       var ADMIN_MENU_SEARCH_URL = "<%= admin_menu_search_path %>";