library: rename Scan nav/page to Library, show audio codecs per row

Per-row audio codec summary (distinct lowercased codecs across an
item's audio streams) via scalar subquery on media_streams, rendered
as "ac3 · aac" in a new monospace Audio column.

v2026.04.15.9

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/__root.tsx

@@ -65,7 +65,7 @@ function RootLayout() {
 				<VersionBadge />
 				<div className="flex flex-wrap items-center gap-0.5">
 					<NavLink to="/" exact>
-						Scan
+						Library
 					</NavLink>
 					<NavLink to="/pipeline">Pipeline</NavLink>
 					<NavLink to="/review/subtitles">Subtitles</NavLink>