[Issue #8956] Remove orphaned attachments from submission zip file

[mikehgrantsgov]

Summary

Fixes #8956

Changes proposed

• process_application_attachments now calls _collect_referenced_attachment_ids() to determine which attachments are actually referenced in form responses before adding them to the submission zip
• Orphaned attachments (uploaded but not referenced in any form field) are skipped with a warning log
• Updated test_run_task to reflect that attachments are orphaned and correctly excluded
• Added test case to cover behavior

Context for reviewers

The orphan detection logic already existed in create_attachment_mapping() to exclude unreferenced attachments from the XML, but wasn't being applied when building the zip. This change wires that same logic into the zip-building step so the zip and XML are consistent.

Validation steps

See updated test cases.

[chouinar]

I'm probably missing some context on this work. The way it currently works is very intentional, I set it up to add all attachments to the ZIP regardless of whether they're referenced from a form because attachments don't need to be on a form in our system. I know we adjusted this in the XML because the legacy system does need that, but ours doesn't.

Is it causing issues for working with the old systems if there are are attachments present in the ZIP? If not, I'd strongly push back against this change as it's removing functionality that is intentionally different from the legacy approach. If a user uploads a file to an application without putting it on a form, what is the user experience to let them know that it will not be included when sent to a grantor?