Why:
- The helper turning a SeedSpec into an upsertable ChunkPoint lived inside one
integration test. A second suite now needs to seed real Qdrant the same way,
and a copy would let the two drift.
Changes:
- Move `_chunk_point` into tests/support/point_contract.py as `chunk_point_for`,
beside the `build_point` read model it derives its payload from.
Impact:
- Pure move. No behaviour change; enables the API suite that follows.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>