The comment tools resolved `id` (the comment's /NM, as comment_list
reports it) to the first annotation with that name. /NM need not be
unique: in a PyMuPDF file every page's first comment is `fitz-A0`, so
comment_reply, comment_set_status and the rest acted on page 1's
comment whatever page the caller meant. A shared id is now refused
with a message pointing at `page` + `index`, which always name one
comment. A new end-to-end test also checks that comment_list threads
such a file by reference.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
