Attachments: attach a file and delete one (panel, edit, tools); duplicate names numbered as text

pdfcraft_organize::add_attachment puts a file in /Names /EmbeddedFiles as a
Filespec with a Flate-compressed EmbeddedFile stream (/Subtype, /Size,
/ModDate), the name made unique; delete_attachment removes one, the last taking
the tree with it. Edit::AddAttachment / Edit::DeleteAttachment (undoable),
Edit ▸ Attach a file… with a button at the top of the Attachments panel and a
trash button on each document-level row, tools attachment_add and
attachment_delete, rows in every language, parity attachments-add and
attachments-delete shipped.

Fixes set_attachments (Combine): a duplicate name was numbered by appending
ASCII bytes, corrupting UTF-16 keys; names are now numbered as text. An
indirect /Names is updated in place instead of replaced, so its /Dests and
/JavaScript stay.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

parity/acrobat-features.toml

@@ -3325,11 +3325,11 @@ title = "Add file attachments"
 area = "D"
 tier = "P2"
 milestone = "M12"
-status = "planned"
-commands = []
-tools = []
-evidence = []
-notes = ""
+status = "shipped"
+commands = ["edit.attach"]
+tools = ["attachment_add"]
+evidence = ["crates/organize/src/tests.rs::attachments_are_added_listed_and_deleted", "crates/organize/src/tests.rs::attachments_added_in_the_app_survive_combine_and_more_can_be_attached", "crates/automation/tests/automation.rs::attaching_and_deleting_files_through_the_tools"]
+notes = "Edit ▸ Attach a file… (also the Attach a file… button in the Attachments panel and the Edit a PDF list): the file goes into /Names /EmbeddedFiles as a Filespec with a Flate-compressed EmbeddedFile stream (/Size, /ModDate, /Subtype from the extension); a name already taken gets \"
 
 [[feature]]
 id = "organize.attachments-delete"
@@ -3337,11 +3337,11 @@ title = "Delete attachments"
 area = "D"
 tier = "P2"
 milestone = "M12"
-status = "planned"
+status = "shipped"
 commands = []
-tools = []
-evidence = []
-notes = ""
+tools = ["attachment_delete"]
+evidence = ["crates/organize/src/tests.rs::attachments_are_added_listed_and_deleted", "crates/organize/src/tests.rs::attachments_added_in_the_app_survive_combine_and_more_can_be_attached", "crates/automation/tests/automation.rs::attaching_and_deleting_files_through_the_tools"]
+notes = "The trash button on a document-level row of the Attachments panel; the last one removed takes the /EmbeddedFiles tree with it. Undoable. A paper-clip comment is deleted as a comment."
 
 [[feature]]
 id = "organize.attachments-description"