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/globals.css

@@ -60,6 +60,30 @@
   --input-border-color: #4b5563;
   --input-focus-color: #eeb425;
   --navbar-height: 64px;
+  /* Aliases used throughout the admin pages' inline styles. */
+  --muted: var(--color-text-muted);
+  --border: color-mix(in srgb, var(--color-text-muted) 18%, transparent);
+}
+
+/* Dark mode (toggled by html.dark; wins over :root + ThemeVars via specificity). */
+html.dark {
+  --color-background: #0f1117;
+  --color-surface: #171a21;
+  --color-dropdown: #1f242d;
+  --color-navbar: #171a21;
+  --color-navbar-text: #e5e7eb;
+  --color-text: #e5e7eb;
+  --color-text-muted: #9ca3af;
+}
+html.dark input,
+html.dark select,
+html.dark textarea {
+  background: #11151c;
+  color: var(--color-text);
+}
+html.dark .currency,
+html.dark .article-img {
+  background: #1f242d;
 }
 
 html {