feat(nav): consolidate Posts/Artists/Tags into a Browse hub

Posts, Artists, and Tags are the three 'browse the library by an axis'
surfaces; Subscriptions stays purely management (operator-asked 2026-06-09).
New BrowseView renders them as tabs (?tab=posts|artists|tags); only the active
tab mounts. The old standalone paths become redirects into the matching tab,
preserving deep-link query (/posts?post_id=N → /browse?tab=posts&post_id=N) and
keeping the route names so existing { name: 'posts'|'artists'|'tags' } links and
path pushes still resolve. Nav now reads Showcase · Gallery · Browse · Series ·
Subscriptions, with Settings pinned right.

Test: /browse resolves; /tags and /artists redirect into their tabs; a posts
deep link survives the redirect.

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

frontend/src/router.js

@@ -2,14 +2,12 @@ import { createRouter, createWebHistory, createMemoryHistory } from 'vue-router'
 import SettingsView from './views/SettingsView.vue'
 import GalleryView from './views/GalleryView.vue'
 import ShowcaseView from './views/ShowcaseView.vue'
-import TagsView from './views/TagsView.vue'
+import BrowseView from './views/BrowseView.vue'
 import ArtistView from './views/ArtistView.vue'
 import SeriesView from './views/SeriesView.vue'
 import SeriesManageView from './views/SeriesManageView.vue'
 import SeriesReaderView from './views/SeriesReaderView.vue'
 import SubscriptionsView from './views/SubscriptionsView.vue'
-import PostsView from './views/PostsView.vue'
-import ArtistsView from './views/ArtistsView.vue'
 
 // The application's front door. `/` redirects here. Changing the front door
 // is a one-line edit (e.g. '/gallery' or '/tags').
@@ -22,27 +20,36 @@ const routes = [
   // FC-2: image backbone
   { path: '/showcase', name: 'showcase', component: ShowcaseView, meta: { title: 'Showcase' } },
   { path: '/gallery',  name: 'gallery',  component: GalleryView,  meta: { title: 'Gallery'  } },
-  { path: '/artists',  name: 'artists',  component: ArtistsView,  meta: { title: 'Artists'  } },
-  { path: '/tags',     name: 'tags',     component: TagsView,     meta: { title: 'Tags'     } },
+  // Browse hub (operator-asked 2026-06-09): Posts / Artists / Tags as tabs —
+  // the three "browse the library by an axis" surfaces. One nav entry; the old
+  // standalone paths redirect into the matching tab (below).
+  { path: '/browse', name: 'browse', component: BrowseView, meta: { title: 'Browse' } },
   // Artist detail — no meta.title (reached by clicking an artist, not nav).
   { path: '/artist/:slug', name: 'artist', component: ArtistView },
-  // Series browse — a nav entry (meta.title). Peer of Posts.
+  // Series browse — a nav entry (meta.title).
   { path: '/series', name: 'series', component: SeriesView, meta: { title: 'Series' } },
   // Series management — no meta.title (reached from a series card/tag).
   { path: '/series/:tagId', name: 'series-manage', component: SeriesManageView },
   // Series reader — immersive (no top nav, no meta.title).
   { path: '/series/:tagId/read', name: 'series-read', component: SeriesReaderView, meta: { immersive: true } },
-  { path: '/settings', name: 'settings', component: SettingsView, meta: { title: 'Settings' } },
 
-  // FC-3: subscription backbone
-  // /credentials and /downloads were folded into /subscriptions as subtabs
-  // 2026-05-27 (?tab=settings and ?tab=downloads). The hub view owns the
-  // whole download pipeline domain.
-  { path: '/posts',         name: 'posts',         component: PostsView,         meta: { title: 'Posts'         } },
+  // FC-3: subscription backbone — purely management (sources/downloads),
+  // distinct from the Browse hub.
   { path: '/subscriptions', name: 'subscriptions', component: SubscriptionsView, meta: { title: 'Subscriptions' } },
 
-  // Bookmark/back-button safety net for the routes that got folded in
-  // (no meta.title — stay out of TopNav).
+  // Settings — config, pinned to the right of the nav (TopNav special-cases it).
+  { path: '/settings', name: 'settings', component: SettingsView, meta: { title: 'Settings' } },
+
+  // The old standalone paths now redirect into the Browse hub, preserving any
+  // deep-link query (e.g. /posts?post_id=N → /browse?tab=posts&post_id=N). The
+  // route NAMES stay so existing { name: 'posts' | 'artists' | 'tags' } links
+  // and path pushes keep resolving.
+  { path: '/posts',   name: 'posts',   redirect: (to) => ({ name: 'browse', query: { ...to.query, tab: 'posts' } }) },
+  { path: '/artists', name: 'artists', redirect: (to) => ({ name: 'browse', query: { ...to.query, tab: 'artists' } }) },
+  { path: '/tags',    name: 'tags',    redirect: (to) => ({ name: 'browse', query: { ...to.query, tab: 'tags' } }) },
+
+  // Bookmark/back-button safety net for the routes that got folded into
+  // /subscriptions (no meta.title — stay out of TopNav).
   { path: '/credentials', redirect: '/subscriptions?tab=settings' },
   { path: '/downloads',   redirect: '/subscriptions?tab=downloads' }
 ]