Split acceptance and benchmark helpers into modules

[yvette-carlisle]

Summary

• split work journal acceptance tests into helper/session/promotion modules
• split graph RAG and dreaming readiness benchmark assertions into focused modules
• split chunk search and structured field retrieval acceptance helpers by context, inserts, qdrant, and rerank responsibilities

Validation

• RUSTC=/run/current-system/sw/bin/rustc cargo make fmt-rust && RUSTC=/run/current-system/sw/bin/rustc cargo make check after work_journal + graph_rag
• RUSTC=/run/current-system/sw/bin/rustc cargo make fmt-rust && RUSTC=/run/current-system/sw/bin/rustc cargo make check after structured_field_retrieval/support
• RUSTC=/run/current-system/sw/bin/rustc cargo make fmt-rust && RUSTC=/run/current-system/sw/bin/rustc cargo make check after chunk_search/tests_helpers
• RUSTC=/run/current-system/sw/bin/rustc cargo make fmt-rust && RUSTC=/run/current-system/sw/bin/rustc cargo make check after dreaming_readiness

Final local check summary: 403 passed, 92 skipped.

Diff size

• 21 files changed, 1858 insertions, 1777 deletions