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).

models/subscription.py

@@ -70,7 +70,7 @@ PLANS = {
         "max_pages_per_doc": 50,
         "max_file_size_mb": 10,
         "max_chars_per_month": 500_000,
-        "providers": ["google", "deepl"],
+        "providers": ["google"],
         "features": [
             "pricing.plans.starter.feat1",
             "pricing.plans.starter.feat2",
@@ -96,7 +96,7 @@ PLANS = {
         "max_pages_per_doc": 200,
         "max_file_size_mb": 25,
         "max_chars_per_month": 2_000_000,
-        "providers": ["google", "google_cloud", "deepl", "openrouter"],
+        "providers": ["google", "google_cloud", "openrouter"],
         "ai_model_essential": "deepseek/deepseek-chat",
         "features": [
             "pricing.plans.pro.feat1",
@@ -126,7 +126,7 @@ PLANS = {
         "max_pages_per_doc": 500,
         "max_file_size_mb": 50,
         "max_chars_per_month": 10_000_000,
-        "providers": ["google", "google_cloud", "deepl", "openrouter", "openrouter_premium", "openai", "zai"],
+        "providers": ["google", "google_cloud", "openrouter", "openrouter_premium", "openai", "zai"],
         "ai_model_essential": "deepseek/deepseek-chat",
         "ai_model_premium": "anthropic/claude-sonnet-4.6",
         "features": [
@@ -161,7 +161,7 @@ PLANS = {
         "max_pages_per_doc": -1,
         "max_file_size_mb": -1,
         "max_chars_per_month": -1,
-        "providers": ["google", "google_cloud", "deepl", "openrouter", "openrouter_premium", "openai", "zai", "custom"],
+        "providers": ["google", "google_cloud", "openrouter", "openrouter_premium", "openai", "zai", "custom"],
         "features": [
             "pricing.plans.enterprise.feat1",
             "pricing.plans.enterprise.feat2",