feat: add pricing checkout flow, MFA type fixes, and Wave 13 audit docs

- Pricing page: enhanced with checkout modal integration, plan
  comparison table, and subscription funnel
- Payment return page: new VNPay/MoMo callback handler
- Subscription components: new checkout-modal with payment method
  selection (VNPay, MoMo, ZaloPay)
- API modules: type-safe PII encryption, improved error handling in
  MFA/auth/payments/analytics/search/notifications modules
- Audit docs: comprehensive Wave 13 platform assessment, pricing
  audit, production readiness checklist
- Updated PROJECT_TRACKER with Wave 13 status

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/messages/en.json

@@ -188,6 +188,11 @@
     "ctaFree": "Register for free",
     "ctaUpgrade": "Get started",
     "ctaEnterprise": "Contact sales",
+    "ctaCurrentPlan": "Current plan",
+    "ctaDowngrade": "Downgrade",
+    "ctaManageSubscription": "Manage subscription",
+    "currentPlan": "Current",
+    "currentPlanBadge": "You are on the {plan} plan",
     "comparisonTitle": "Compare plans in detail",
     "comparisonSubtitle": "See all features for each plan",
     "feature": "Feature",

apps/web/messages/vi.json

@@ -188,6 +188,11 @@
     "ctaFree": "Đăng ký miễn phí",
     "ctaUpgrade": "Bắt đầu ngay",
     "ctaEnterprise": "Liên hệ tư vấn",
+    "ctaCurrentPlan": "Gói hiện tại",
+    "ctaDowngrade": "Hạ gói",
+    "ctaManageSubscription": "Quản lý gói dịch vụ",
+    "currentPlan": "Hiện tại",
+    "currentPlanBadge": "Bạn đang sử dụng gói {plan}",
     "comparisonTitle": "So sánh chi tiết các gói",
     "comparisonSubtitle": "Xem đầy đủ tính năng của từng gói dịch vụ",
     "feature": "Tính năng",