Add ownership validation to prevent users from deleting or embedding
parsed files that don't belong to them. Previously, the delete and
embed endpoints only validated authentication but not resource ownership,
allowing users to delete attached files for users within workspaces they are also a member of.
Changes:
- Delete endpoint now filters by userId and workspaceId
- Embed endpoint validates file belongs to user and workspace (redundant)
- delete() returns false when no matching records found (returns 403)
- Added JSDoc comments for clarity
GHSA-p5rf-8p88-979c
f2030343d7