Release v0.51.471 — searchable settings (#3850)

Ships @rodboev's searchable-settings feature (#3850/#3936): a search box in
Settings that finds any field across all 5 sections with breadcrumbs +
click-to-navigate+highlight+clear. Rebased fresh onto master (post v0.51.470),
5 feature files byte-identical to PR head, re-stamped v0.51.471 (was v0.51.469,
collided with the shipped transcript-virtualization release).

Co-authored-by: Rod Boev <rod.boev@gmail.com>

CHANGELOG.md

@@ -3,6 +3,12 @@
 
 ## [Unreleased]
 
+## [v0.51.471] — 2026-06-17 — Release QF (searchable settings)
+
+### Added
+
+- **Settings is now searchable (#3850).** A search box at the top of the Settings panel lets you find any setting across all sections (Appearance, Preferences, Providers, Plugins, System) without clicking through tabs — type a label fragment (e.g. "model", "theme", "language") and matching fields appear in a dropdown with their section breadcrumb. Clicking a result jumps to that section, scrolls the field into view, and pulses a brief highlight on it. Search clears after a pick. The index is built once on first search (covering lazily-loaded provider/plugin cards) and memoized. Thanks @rodboev.
+
 ## [v0.51.470] — 2026-06-17 — Release QE (transcript virtualization now experimental / off by default)
 
 ### Changed