🐛 Absorb a deleted library into the files that used it

Deleting a shared library removes its links to the files using it at
once, so they stop listing it, and queues the delete-object job, which
absorbs the library into the files it finds through those links. By
then there were none, so nothing was absorbed: the files lost the
library and their copies kept pointing at the deleted file
(PENPOT-1092). Unpublishing absorbs before it unlinks, so it was not
affected.

The delete reads the files using the library before unlinking them
and gives them to the job (:absorb-file-ids), which absorbs into them;
without them, as from the project and team deletions, the job still
finds them through the links.

rpc-file-test/delete-shared-library-absorbs-it-into-the-files-using-it
deletes the library through the RPC and runs the job it queued.

AI-assisted-by: claude-opus-5-5

backend/test/backend_tests/rpc_file_test.clj

@@ -2219,6 +2219,16 @@
                                      :is-shared false})))
     (check-absorbed! setup)))
 
+(t/deftest delete-shared-library-absorbs-it-into-the-files-using-it
+  ;; Deleting the file unlinks it from its users at once; the job that
+  ;; follows must still find them and give them the components they use.
+  (let [{:keys [profile library] :as setup} (create-library-copy!)]
+    (t/is (th/success? (th/command! {::th/type :delete-file
+                                     ::rpc/profile-id (:id profile)
+                                     :id (:id library)})))
+    (th/run-pending-jobs)
+    (check-absorbed! setup)))
+
 (t/deftest delete-shared-library-with-storage-file-data
   (binding [cf/config (assoc cf/config :file-data-backend "storage")]
     ;; Keep this test focused on the storage-backed file-data fix: create