Add dark mode, i18n, messenger/moderation/verify, admin CRUD parity

Web-tier features completing the AtomCMS→Next.js conversion (slice 2):

UI/UX:
- Dark mode: html.dark CSS-var overrides + ThemeSwitcher (localStorage,
  no-flash boot script) wired into the nav.
- i18n (next-intl, cookie-based / no URL routing): en + it catalogs,
  request.ts, provider in root layout, LanguageSwitcher; shell (nav,
  header, footer) fully translated. URLs + access-guard unchanged.
- globals.css: --muted/--border aliases used across admin pages.

User features:
- /messages: offline messages + friend-request accept (server action
  re-reads session, two directional rows, idempotent).
- Email verification: signed-token /verify route + sendVerification wired
  into register (best-effort, never blocks signup).
- Article reactions: toggle UI on news/[slug] + server action.
- Content moderation service (website_wordfilter + optional OpenAI
  moderations, fail-open) wired into article comments + guestbook.

Admin CRUD parity (Filament replacement):
- /admin/shop (+ new/[id]) packages CRUD + read-only orders.
- /admin/transactions read-only PayPal log.
- /admin/permissions, /admin/tags, /admin/ads (+ new/[id]),
  /admin/help-questions (+ new/[id]), /admin/radio/history,
  /admin/users/[id]/edit. All gated by requireStaff + logStaffActivity.

Verified: tsc 0, vitest 48/48, next build 0 (all routes incl. new
admin CRUD + /messages + /verify).

src/app/admin/layout.tsx

@@ -29,10 +29,14 @@ export default async function AdminLayout({ children }: { children: ReactNode })
           <Link href="/admin/users">Users</Link>
           <Link href="/admin/rooms">Rooms</Link>
           <Link href="/admin/articles">Articles</Link>
+          <Link href="/admin/tags">Tags</Link>
           <Link href="/admin/catalog">Catalog</Link>
+          <Link href="/admin/shop">Shop</Link>
+          <Link href="/admin/transactions">Transactions</Link>
           <Link href="/admin/vouchers">Vouchers</Link>
           <Link href="/admin/badges">Badges</Link>
           <Link href="/admin/radio">Radio</Link>
+          <Link href="/admin/radio/history">Radio History</Link>
           <Link href="/admin/achievements">Achievements</Link>
           <Link href="/admin/subscriptions">Subscriptions</Link>
           <Link href="/admin/calendar">Calendar</Link>
@@ -40,6 +44,8 @@ export default async function AdminLayout({ children }: { children: ReactNode })
           <Link href="/admin/photos">Photos</Link>
           <Link href="/admin/bans">Bans</Link>
           <Link href="/admin/applications">Applications</Link>
+          <Link href="/admin/help-questions">Help Center</Link>
+          <Link href="/admin/ads">Advertisements</Link>
           <Link href="/admin/wordfilter">Word Filter</Link>
           <Link href="/admin/ip">IP Management</Link>
           <Link href="/admin/logs">Logs</Link>