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/components/landing/landing-page.tsx

@@ -143,29 +143,6 @@ const Hero = () => {
                 referrerPolicy="no-referrer"
               />
               <div className="absolute inset-0 bg-brand-dark/5 dark:bg-black/20" />
-
-              <div className="absolute top-8 right-8 w-64 bg-white/90 dark:bg-[#1a1a1a]/90 backdrop-blur-xl border border-black/5 dark:border-white/10 p-6 rounded-2xl shadow-2xl text-left hidden md:block">
-                <div className="flex items-center gap-3 mb-4">
-                  <div className="w-8 h-8 rounded-full bg-brand-accent/20 flex items-center justify-center text-brand-accent">
-                    <Zap size={16} />
-                  </div>
-                  <span className="text-[10px] font-bold uppercase tracking-widest text-brand-dark dark:text-white">Context Engine</span>
-                </div>
-                <p className="text-xs text-brand-dark/70 dark:text-white/70 leading-relaxed font-medium">{t('landing.hero.contextEngine')}</p>
-              </div>
-
-              <div className="absolute bottom-8 left-8 w-64 bg-brand-dark dark:bg-[#0a0a0a] text-white p-6 rounded-2xl shadow-2xl text-left hidden md:block">
-                <div className="flex items-center gap-3 mb-4">
-                  <Activity size={16} className="text-brand-accent" />
-                  <span className="text-[10px] font-bold uppercase tracking-widest text-brand-accent">{t('landing.hero.liveAnalysis')}</span>
-                </div>
-                <div className="flex items-center gap-3">
-                  {[1, 2, 3].map(i => (
-                    <div key={i} className="w-6 h-6 rounded-full border-2 border-brand-dark dark:border-[#0a0a0a] bg-brand-muted dark:bg-[#1f1f1f] text-[8px] flex items-center justify-center font-bold text-brand-dark dark:text-white">JD</div>
-                  ))}
-                  <span className="text-[10px] ml-2 text-white/60">+12 {t('landing.hero.termsDetected')}</span>
-                </div>
-              </div>
             </div>
           </div>
         </motion.div>