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).

routes/admin_routes.py

@@ -337,7 +337,6 @@ async def get_admin_dashboard(admin_id: str = Depends(require_admin)):
                 "label": label,
             }
 
-        _engine_status("deepl", "DEEPL_API_KEY", "DeepL")
         _engine_status("openrouter", "OPENROUTER_API_KEY", "Traduction IA Éco")
         _engine_status("openrouter_premium", "OPENROUTER_API_KEY", "Traduction IA Premium")
         _engine_status("openai", "OPENAI_API_KEY", "OpenAI")
@@ -712,7 +711,6 @@ async def update_default_provider(
     valid_providers = [
         "google",
         "google_cloud",
-        "deepl",
         "openai",
         "openrouter",
         "openrouter_premium",
@@ -916,7 +914,6 @@ class SmtpSettings(BaseModel):
 class SettingsConfig(BaseModel):
     google: ProviderSettings = ProviderSettings(enabled=True)
     google_cloud: ProviderSettings = ProviderSettings()    # Cloud Translation API v2 (clé API)
-    deepl: ProviderSettings = ProviderSettings()
     openai: ProviderSettings = ProviderSettings()
 
     openrouter: ProviderSettings = ProviderSettings()      # "Traduction IA Essentielle"
@@ -926,8 +923,8 @@ class SettingsConfig(BaseModel):
     zai: ProviderSettings = ProviderSettings()
     mistral: ProviderSettings = ProviderSettings()         # OCR Mistral (PDF scannés)
     smtp: SmtpSettings = SmtpSettings()
-    fallback_chain: str = "google,google_cloud,deepl,openrouter,openrouter_premium,openai,deepseek,zai"
-    fallback_chain_classic: str = "google,google_cloud,deepl"
+    fallback_chain: str = "google,google_cloud,openrouter,openrouter_premium,openai,deepseek,zai"
+    fallback_chain_classic: str = "google,google_cloud"
     fallback_chain_llm: str = "openrouter,openrouter_premium,openai,deepseek,zai"
 
 
@@ -991,7 +988,6 @@ async def get_settings(admin_id: str = Depends(require_admin)):
     # Premium : Claude Sonnet 4.6 — précision maximale sur documents complexes
     payload["openrouter_premium"] = _merge_env(settings.openrouter_premium, key_env="OPENROUTER_API_KEY",         model_env="OPENROUTER_PREMIUM_MODEL",  default_model="anthropic/claude-sonnet-4.6")
     payload["openai"]             = _merge_env(settings.openai,             key_env="OPENAI_API_KEY",             model_env="OPENAI_MODEL",             default_model="gpt-4o-mini")
-    payload["deepl"]              = _merge_env(settings.deepl,              key_env="DEEPL_API_KEY")
     payload["deepseek"]           = _merge_env(settings.deepseek,           key_env="DEEPSEEK_API_KEY",     model_env="DEEPSEEK_MODEL",     default_model="deepseek-chat")
     payload["minimax"]            = _merge_env(settings.minimax,            key_env="MINIMAX_API_KEY",      model_env="MINIMAX_MODEL",      default_model="abab6.5s-chat")
     payload["zai"]                = _merge_env(settings.zai,                key_env="ZAI_API_KEY",                model_env="ZAI_MODEL",                url_env="ZAI_BASE_URL",  default_model="grok-2-1212", default_url="https://api.x.ai/v1")
@@ -1023,7 +1019,6 @@ async def get_settings(admin_id: str = Depends(require_admin)):
     # (boolean only — never expose actual values)
     has_openrouter = bool(os.getenv("OPENROUTER_API_KEY", "").strip())
     env_info = {
-        "deepl":              bool(os.getenv("DEEPL_API_KEY", "").strip()),
         "openai":             bool(os.getenv("OPENAI_API_KEY", "").strip()),
         "openrouter":         has_openrouter,
         "openrouter_premium": has_openrouter,  # same key, different model
@@ -1193,20 +1188,6 @@ async def test_provider(
                     },
                 )
 
-        elif provider == "deepl":
-            api_key = _key(provider_config.api_key, "DEEPL_API_KEY")
-            if not api_key:
-                return JSONResponse(
-                    status_code=400,
-                    content={"available": False, "error": "Aucune clé API DeepL trouvée (JSON ou .env)"},
-                )
-            import deepl
-
-            translator = deepl.Translator(api_key)
-            usage = translator.get_usage()
-            return JSONResponse(
-                status_code=200, content={"available": True, "usage": str(usage)}
-            )
 
         elif provider == "openrouter_premium":
             current.openrouter_premium = _update_provider(current.openrouter_premium, update_data)