Modularize service acceptance test helpers

[yvette-carlisle]

Summary

• Split service acceptance helper monoliths into Rust modules with explicit file-module boundaries.
• Modularized consolidation, graph ingestion, knowledge page source inserts, English-only boundary tests, and service tests.
• Preserved existing public helper surfaces through root module reexports.

Validation

• After each segment: RUSTC=/run/current-system/sw/bin/rustc cargo make fmt-rust && RUSTC=/run/current-system/sw/bin/rustc cargo make check
• Final local result: 403 tests run: 403 passed, 92 skipped

Batch size

• 28 files changed, 1711 insertions, 1619 deletions, 3330 total changed lines