Add erfa/chaostreff node-kind creation conventions

lib/ccc_conventions.rb: NODE_KINDS registry replaces the kind-specific
branches previously scattered across nodes_controller#create (tags),
unique_path-position check). Each kind declares its parent lookup
(a Proc - Update's "update"/"press_release" continue to genuinely
find-or-create their year-folder via Update.find_or_create_parent;
erfa/chaostreff use a plain find_by_unique_name!, since their parent
nodes are fixed and a missing one should fail loudly, not be silently
created), its tags, and (new) its default template.

Node gains a default_template_name column (migration, with backfill
for existing update-tree nodes via node.update? - reusing that method
rather than re-deriving its unique_path check in raw SQL). Page#set_template
now inherits from node.default_template_name, falling back to the old
update?-based check only when the column is blank, and only fills in
template_name when nothing's already been explicitly chosen - a
deliberate change from the previous behavior, which unconditionally
overwrote template_name on every save regardless of manual selection.
Node#update? itself is unchanged and still used as-is by
admin_controller's sitemap filtering - a genuinely different, still
valid use of that check.

"generic" stays special-cased in the controller, parametrized by
params[:parent_id] at request time - doesn't fit "kind implies a fixed
lookup" and isn't in the registry.

nodes#new's four hardcoded radio buttons and nodes_controller's
kind-specific case/when branches are both replaced by iterating/looking
up this one registry - adding a new kind now means one new hash entry,
not four scattered edits.

1 files changed, 4 insertions, 0 deletions

diff --git a/config/routes.rb b/config/routes.rb
index a7775b3..cf4733c 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -31,6 +31,10 @@ Cccms::Application.routes.draw do
     end
 
     resources :nodes do
+      collection do
+        get :parameterize_preview
+      end
+
       member do
         put :unlock
         put :publish