fix: remove DeepSeek/MiniMax branding, fix glossary visibility, improve translate page UX

- US1: Replace exposed provider names (DeepSeek V3 → IA Express, MiniMax → IA Avancée)
  in legacy_routes.py, remove 52 DeepSeek references from i18n pricing/landing keys,
  add generic modelName key across all 13 languages
- US2: Fix glossary selector filtering (fallback to all glossaries when source lang
  filter returns empty), show templates by default, fix 3 broken presets
  (hvac/construction/automotive → hr/scientific/ecommerce)
- US3: Replace 15 hardcoded French strings with i18n t() calls, increase font sizes
  from 8-9px to 11px, improve text contrast (opacity /20→/40, /25→/45, /30→/50)
- US4: Add missing provider labels in admin ProviderStatus (deepseek, minimax, zai,
  google_cloud, openrouter, openrouter_premium)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/app/pricing/page.tsx

@@ -814,7 +814,7 @@ export default function PricingPage() {
                 <Badge className="ml-auto text-xs bg-blue-500/10 text-blue-600 border-blue-500/30 dark:text-blue-300">{t('pricing.aiModels.essential.plan')}</Badge>
               </div>
               <div className="text-sm text-muted-foreground mb-3">
-                {t('pricing.aiModels.essential.descPrefix')} <strong className="text-foreground">DeepSeek V3.2</strong> {t('pricing.aiModels.essential.descSuffix')}
+                {t('pricing.aiModels.essential.descPrefix')} <strong className="text-foreground">{t('pricing.aiModels.essential.modelName')}</strong> {t('pricing.aiModels.essential.descSuffix')}
               </div>
               <div className="flex flex-wrap gap-2 text-xs">
                 <span className="px-2 py-1 bg-muted rounded">{t('pricing.aiModels.essential.context')}</span>