feat: billing v2 — runtime-based plans, English UI, payment flow

- ServicePlan now has 'runtime' field (nodejs/laravel/wordpress)
- Admin billing page: Application Type dropdown, English UI, Toman prices
- calculateCost filters active plans by matching runtime
- Wallet page: English UI, payment gateway integration (Pay Now button)
- Deploy page Review step: billing cycle selector (hourly/monthly/yearly),
  payment method choice (wallet or payment gateway), Pay & Deploy button
- Payment gateway endpoints: POST /billing/gateway/initiate + /verify
  (simulated — ready for Zarinpal/IDPay integration)
- Deploy requires payment: wallet deduction or gateway charge before deploy

frontend/src/types/index.ts

@@ -257,6 +257,7 @@ export interface PricingRule {
 export interface ServicePlan {
   id: string;
   name: string;
+  runtime: 'nodejs' | 'laravel' | 'wordpress';
   description?: string;
   billingCycle: BillingCycle;
   isActive: boolean;