Three follow-ups from Task 7 code review:
1. Drop the dead interest.yachtId fallback branch. interests.clientId
is NOT NULL so the yacht branch was unreachable. Comment explains
the schema constraint so the branch can be re-added if that
constraint is ever relaxed.
2. Add defense-in-depth port_id filter to the interests lookup
inside resolveDocumentOwner (matches CLAUDE.md convention and
every other interests query in this file).
3. Add two integration test cases for direct-company and direct-yacht
owner resolution — closes the coverage gap where the signed-file
row's companyId/yachtId columns are populated for the first time
in this commit chain.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>