fix(router): reset tab title on navigation (artist name stuck on other tabs)

ArtistView set document.title to "<artist> — FabledCurator" on load but nothing
reset it when navigating away, so the artist name stuck on the Showcase/Gallery
tab title (operator-flagged 2026-06-07). Add a router.afterEach that sets the
title from meta.title on every navigation; detail views with no meta.title reset
to the default and then set their own dynamic title.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/router.js

@@ -54,4 +54,19 @@ const router = createRouter({
   routes
 })
 
+const DEFAULT_TITLE = 'FabledCurator'
+
+// Keep the tab title in sync with the route on EVERY navigation. List routes set
+// it from meta.title; detail routes (artist, series) have no meta.title, so they
+// reset to the default here and then overwrite it with their own dynamic title
+// (e.g. ArtistView sets "<artist> — FabledCurator"). Without this reset the
+// previous view's dynamic title stuck around — an artist name showing on the
+// Showcase tab, operator-flagged 2026-06-07.
+router.afterEach((to) => {
+  if (typeof document === 'undefined') return
+  document.title = to.meta?.title
+    ? `${to.meta.title} — ${DEFAULT_TITLE}`
+    : DEFAULT_TITLE
+})
+
 export default router