The pipeline admin form could never save

`ActiveAdmin.register WarpEngine::Pipeline` declared no `permit_params`, so every edit
handed unpermitted attributes to the model and Rails raised ForbiddenAttributesError. That
is not new: the form has been unable to save for as long as it has existed. My flash
message on `update` sat at the top of the traceback and made it look like the cause, which
it was not — and it is gone anyway, because overriding an ActiveAdmin action to say
something is a poor trade for what it can break. The move is written to the log instead.

Adding a spec that would have caught it, in the host app, because that is where the
ActiveAdmin instance lives: it signs in, PUTs the form, and checks both that the record
saves and that the software link moves off the pipeline that had it. Driven the same way
by hand against the development database first — 302, the link moved, the previous holder
left without one.

The engine's other admin resources were checked for the same omission: downloads and
releases are read-only and the file manager posts to its own routes, so pipelines was the
only one affected.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/models/warp_engine/pipeline.rb

@@ -55,6 +55,16 @@ module WarpEngine
 
       others = Pipeline.where(software_id: software_id).where.not(id: id)
       @software_taken_from = others.map(&:full_name)
+      return if @software_taken_from.empty?
+
+      # Logged rather than flashed. The first attempt at this put a message on screen by
+      # overriding the admin's `update` action, which bypassed the permitted-params path
+      # and made every pipeline edit fail with ForbiddenAttributesError. A silent
+      # reassignment is a small problem; an admin page that cannot save is a large one.
+      Rails.logger.info(
+        "[WarpEngine::Pipeline] #{full_name} took software #{software_id} from " \
+        "#{@software_taken_from.join(', ')}"
+      )
       others.update_all(software_id: nil, updated_at: Time.current)
     end