feat(i18n): Comprehensive internationalization of frontend components and pages

Translate all hardcoded English strings to use i18n translation keys:

Components:
- TransactionDetailModal: payment details, refunds, technical info
- ConnectOnboarding/ConnectOnboardingEmbed: Stripe Connect setup
- StripeApiKeysForm: API key management
- DomainPurchase: domain registration flow
- Sidebar: navigation labels
- Schedule/Sidebar, PendingSidebar: scheduler UI
- MasqueradeBanner: masquerade status
- Dashboard widgets: metrics, capacity, customers, tickets
- Marketing: PricingTable, PluginShowcase, BenefitsSection
- ConfirmationModal, ServiceList: common UI

Pages:
- Staff: invitation flow, role management
- Customers: form placeholders
- Payments: transactions, payouts, billing
- BookingSettings: URL and redirect configuration
- TrialExpired: upgrade prompts and features
- PlatformSettings, PlatformBusinesses: admin UI
- HelpApiDocs: API documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/src/components/marketing/BenefitsSection.tsx

@@ -1,33 +1,36 @@
 import React from 'react';
+import { useTranslation } from 'react-i18next';
 import { Rocket, Shield, Zap, Headphones } from 'lucide-react';
 
 const BenefitsSection: React.FC = () => {
+    const { t } = useTranslation();
+
     const benefits = [
         {
             icon: Rocket,
-            title: 'Rapid Deployment',
-            description: 'Launch your branded booking portal in minutes with our pre-configured industry templates.',
+            title: t('marketing.benefits.rapidDeployment.title'),
+            description: t('marketing.benefits.rapidDeployment.description'),
             color: 'text-blue-600 dark:text-blue-400',
             bgColor: 'bg-blue-100 dark:bg-blue-900/30',
         },
         {
             icon: Shield,
-            title: 'Enterprise Security',
-            description: 'Sleep soundly knowing your data is physically isolated in its own dedicated secure vault.',
+            title: t('marketing.benefits.enterpriseSecurity.title'),
+            description: t('marketing.benefits.enterpriseSecurity.description'),
             color: 'text-green-600 dark:text-green-400',
             bgColor: 'bg-green-100 dark:bg-green-900/30',
         },
         {
             icon: Zap,
-            title: 'High Performance',
-            description: 'Built on a modern, edge-cached architecture to ensure instant loading times globally.',
+            title: t('marketing.benefits.highPerformance.title'),
+            description: t('marketing.benefits.highPerformance.description'),
             color: 'text-purple-600 dark:text-purple-400',
             bgColor: 'bg-purple-100 dark:bg-purple-900/30',
         },
         {
             icon: Headphones,
-            title: 'Expert Support',
-            description: 'Our team of scheduling experts is available to help you optimize your automation workflows.',
+            title: t('marketing.benefits.expertSupport.title'),
+            description: t('marketing.benefits.expertSupport.description'),
             color: 'text-orange-600 dark:text-orange-400',
             bgColor: 'bg-orange-100 dark:bg-orange-900/30',
         },