feat(landing,billing): public pricing, global discount, services bar & estimator

Backend
- Add platform-wide global discount (platform_settings: global_discount_percent),
  applied centrally in PricingCatalogService.computeTotalsFromDb so it reaches
  every real charge (previews, deploys, renewals, upgrades, invoices). Admin
  GET/PATCH /billing/settings/global-discount.
- Add unauthenticated PublicPricingController (catalog + calculate) for the
  public landing page, returning gross/net and the discount percentage.
- Bill application replicas by the user-selected footprint: app CPU/RAM/storage
  now all scale by replica count; the single-replica database stays unscaled.

Frontend
- Landing: Services bar (PaaS active, DBaaS, KaaS/LaaS "coming soon" with
  expandable runtime/database menus), transparent Pricing section (per-resource
  rate cards with cycle toggle + discount strikethrough), and a cost Estimator
  ("estimate your package").
- Optional services and the database are priced like runtimes: the estimator
  lets users pick their CPU/RAM/storage (and DB type) so the cost scales by need.
- Admin billing: global-discount editor.
- i18n: fa/en strings for services, pricing, estimator and global discount.

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

frontend/src/i18n/dictionaries/en.ts

@@ -66,6 +66,32 @@ const en: Dictionary = {
       ctaSecondary: 'Sign in',
       scrollHint: 'Dive into the clouds',
     },
+    services: {
+      title: 'Platform services',
+      subtitle: 'Everything you need to build and run your product, in one place.',
+      comingSoon: 'Coming soon',
+      explore: 'Click to explore',
+      paas: {
+        label: 'PaaS',
+        name: 'Platform as a Service',
+        desc: 'Ship your app straight from code to Kubernetes — automatic build and release.',
+      },
+      dbaas: {
+        label: 'DBaaS',
+        name: 'Database as a Service',
+        desc: 'Managed, reliable databases ready in seconds.',
+      },
+      kaas: {
+        label: 'KaaS',
+        name: 'Kubernetes as a Service',
+        desc: 'A dedicated, managed Kubernetes cluster for your team.',
+      },
+      laas: {
+        label: 'LaaS',
+        name: 'Logging as a Service',
+        desc: 'Centralized log collection, retention and analysis.',
+      },
+    },
     value: {
       lead: 'A ',
       highlight: 'self-service PaaS',
@@ -103,6 +129,53 @@ const en: Dictionary = {
         { kpi: 'Iran-native', label: 'Optimized for Iranian users' },
       ],
     },
+    pricing: {
+      title: 'Transparent pricing',
+      subtitle: 'Pay only for the resources you use. These rates are read straight from the platform’s active plans.',
+      runtimeLabel: 'Application type',
+      cycle: { hourly: 'Hourly', monthly: 'Monthly', yearly: 'Yearly' },
+      perCycle: { hourly: 'per hour', monthly: 'per month', yearly: 'per year' },
+      discountBadge: '{p}% off',
+      free: 'Free',
+      resources: {
+        base_fee: 'Base fee',
+        cpu_per_core: 'CPU (per core)',
+        memory_per_gb: 'Memory (per GB)',
+        storage_per_gb: 'Storage (per GB)',
+        database_addon: 'Managed database',
+        custom_domain_addon: 'Custom domain + SSL',
+      },
+      currency: 'Toman',
+      note: 'Your final bill is based on actual usage; these are the per-unit rates for each resource.',
+      loadError: 'Could not load pricing.',
+    },
+    estimator: {
+      title: 'Estimate your package',
+      subtitle: 'Pick the resources you need and see an instant cost estimate.',
+      runtime: 'Application type',
+      cpu: 'CPU',
+      memory: 'Memory (RAM)',
+      storage: 'Storage',
+      replicas: 'Replicas',
+      database: 'Database',
+      databaseType: 'Database type',
+      options: 'Add-on services',
+      redis: 'Redis',
+      rabbitmq: 'RabbitMQ',
+      elasticsearch: 'Elasticsearch (logging)',
+      customDomain: 'Custom domain + SSL',
+      cores: '{n} cores',
+      gb: '{n} GB',
+      none: 'None',
+      estimatedTitle: 'Estimated cost',
+      perCycle: { hourly: 'per hour', monthly: 'per month', yearly: 'per year' },
+      cycle: { hourly: 'Hourly', monthly: 'Monthly', yearly: 'Yearly' },
+      youSave: '{p}% discount applied',
+      calculating: 'Calculating…',
+      cta: 'Build this package',
+      currency: 'Toman',
+      error: 'Could not calculate cost.',
+    },
     finalCta: {
       titleLead: 'The sky is clear; it’s time to ',
       titleHighlight: 'go live',
@@ -1103,6 +1176,19 @@ const en: Dictionary = {
       saveFailedShort: 'Failed to save',
       hours: 'hours',
       days: 'days',
+      globalDiscount: {
+        title: 'Platform-wide discount',
+        subtitle: 'A single percentage applied to every price and real invoice. 0 means no discount.',
+        label: 'Global discount %',
+        hint: 'A number between 0 and 100',
+        save: 'Save discount',
+        saving: 'Saving…',
+        saved: 'Global discount saved',
+        edit: 'Edit',
+        cancel: 'Cancel',
+        none: 'No platform-wide discount is currently active.',
+        active: 'A {p}% discount is active on all services.',
+      },
       discounts: {
         title: 'Discount codes',
         subtitle: 'Percentage discounts on different services — public or for specific users.',