feat(ui,api): wave 3 — editorial pricing, real cancel, server history, DeepL purge

Pricing: full editorial redesign — serif card headers with accent pills
replace the colored font-black blocks, tone sweep across toggle/metrics/
features/CTAs, PLAN_COLORS removed; one design system app-wide.

Translate: decorative titles one step down (CTA hierarchy restored);
glossary and image-translation blocks hidden entirely for free users
(progressive disclosure — three controls for free).

Reviews: XLIFF hint line explains the exchange format; backend errors
routed through a friendly mapper (session/not-found/rate-limit/server).

Landing: fabricated hero UI cards (fake 'Context Engine' overlay)
removed — the photo no longer promises screens that don't exist.

Nav: single DashboardNavLinks component shared by sidebar and mobile
drawer (was duplicated markup).

API: GET /api/v1/translations (user job history, paginated; completed
jobs retained 24h) and POST /api/v1/translations/{id}/cancel —
cooperative cancellation with worker checkpoints before dispatch and
before finalisation, reserved quota released immediately. Translate
monitor now offers a real 'Cancel translation' next to 'Back to start';
recent-jobs list reads server history first, localStorage fallback.

DeepL purge (backend): provider module, registry registration, config
attrs/defaults, dispatch branch, admin settings schema + test branch,
legacy availability block, validation rules, plan provider lists,
error-code mappings, MCP enums, translator prompt mention, related
tests updated/removed. Fallback resolver skips unknown providers, so
stale chains containing 'deepl' degrade gracefully.

Verified: backend 110 tests passed; frontend build exit 0, vitest 9/9,
0 missing i18n keys, eslint 63 errors (vs 64 at HEAD).

frontend/src/app/dashboard/DashboardSidebar.tsx

@@ -1,24 +1,19 @@
 'use client';
 
 import Link from 'next/link';
-import { usePathname } from 'next/navigation';
 import { LogOut } from 'lucide-react';
-import { cn } from '@/lib/utils';
 import { useUser } from './useUser';
 import { useLogout } from './useLogout';
-import { baseNavItems } from './constants';
+import { DashboardNavLinks } from './DashboardNavLinks';
 import { getInitials, translateTier } from './utils';
 import { ThemeToggle } from '@/components/ui/theme-toggle';
 import { useI18n } from '@/lib/i18n';
 
 export function DashboardSidebar() {
-  const pathname = usePathname();
   const { data: user, isLoading } = useUser();
   const { logout } = useLogout();
   const { t } = useI18n();
 
-  const isPro = ['pro', 'business', 'enterprise'].includes(user?.tier ?? '');
-  const navItems = isPro ? baseNavItems : baseNavItems.filter(item => !item.proOnly);
 
   return (
     <aside className="hidden w-72 shrink-0 border-r border-black/5 dark:border-white/5 bg-white dark:bg-[#141414] lg:flex lg:flex-col">
@@ -35,24 +30,7 @@ export function DashboardSidebar() {
       {/* Navigation */}
       <nav className="flex-1 overflow-y-auto px-3 py-2">
         <div className="flex flex-col gap-1">
-          {navItems.map((item) => {
-            const isActive = pathname === item.href;
-            return (
-              <Link
-                key={item.href}
-                href={item.href}
-                className={cn(
-                  'flex items-center gap-4 rounded-2xl px-6 py-4 text-[11px] font-black uppercase tracking-[0.2em] transition-all duration-200',
-                  isActive
-                    ? 'bg-brand-dark text-white shadow-xl'
-                    : 'text-brand-dark/65 dark:text-white/65 hover:bg-brand-muted dark:hover:bg-[#1f1f1f]'
-                )}
-              >
-                <item.icon size={18} className="shrink-0" />
-                {t(item.labelKey)}
-              </Link>
-            );
-          })}
+          <DashboardNavLinks />
         </div>
       </nav>