Stage 7 click-testing fixes (2)

- nodes_controller: permit staged_slug and staged_parent_id in node
  params; these were silently dropped since strong parameters migration,
  breaking the two-phase slug/parent change workflow
- file_attachment: add SVG support; vector files are copied to all style
  directories without rasterisation, preserving scalability in the browser
- assets index/show: constrain image display with max-width/max-height
  via admin.css td img rule; fixes oversized SVG thumbnails while leaving
  raster variants unaffected

1 files changed, 1 insertions, 1 deletions

diff --git a/app/controllers/nodes_controller.rb b/app/controllers/nodes_controller.rb
index bd60b27..494887d 100644
--- a/app/controllers/nodes_controller.rb
+++ b/app/controllers/nodes_controller.rb
@@ -107,7 +107,7 @@ class NodesController < ApplicationController
   private
 
     def node_params
-      params.fetch(:node, {}).permit(:slug, :parent_id)
+      params.fetch(:node, {}).permit(:slug, :parent_id, :staged_slug, :staged_parent_id)
     end
 
     def page_params