Architect how Assembler-generated PDF resource ID is assigned and handled
Depending on the defaults and options we decide on in #3 (closed), we need to architect:
- how Assembler-generated PDFs are cataloged
- for example, if we determine they're an attachment by default they'll be assigned to the attachments family and output to _attachments in pub
- how Assembler-generated PDF resource IDs are handled from the source content and site UI
- are there operation ordering or extension point concerns