Replace the frontend-facing Vector<String> flow with structured
AutocompleteSuggestion objects carrying source, section, title,
and favicon metadata.
Build merged history and literal-URL rows in LibWebView, deduplicate
equivalent URL suggestions, move the autocomplete URL helpers out
of URL.h, and update the history and URL tests around the new model.
Record visits as soon as a page produces useful metadata such as a
title or favicon so pages that never finish loading still become
autocomplete candidates.
Store favicons in the history schema from the start instead of
introducing an upgrade path inside this series, and cover persisted
metadata behavior in TestHistoryStore.
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.
