Teach LibWebView autocomplete to query HistoryStore before falling back
to remote engines and move the wiring out of the AppKit frontend.
Refine matching so scheme and www. boilerplate do not dominate results,
short title and substring queries stay quiet, and history tracing can
explain what the ranking code is doing.
Add a HistoryStore abstraction with transient and persisted backends,
normalize recorded URLs, and skip non-browsable schemes.
Cover lookup and persistence in TestHistoryStore so history-driven
features can share one backend.
