Split service and storage modules

[yvette-carlisle]

Summary

• split progressive search type, search filter parser, ranking text, and diversity selection logic into Rust modules
• split provenance history event construction and storage knowledge writes into focused modules
• keep existing public facades and crate-facing APIs intact while tightening internal ownership boundaries

Validation

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

Size

• 41 files changed, 1626 insertions, 1506 deletions (3132 changed lines)