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

backend/src/billing/dto/billing.dto.ts

@@ -1,7 +1,7 @@
 import { IsString, IsEnum, IsOptional, IsBoolean, IsNumber, IsArray, ValidateNested, Min } from 'class-validator';
 import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
 import { Type } from 'class-transformer';
-import { BillingCycle, PricingResourceType } from '../../common/enums';
+import { BillingCycle, PricingResourceType, AppRuntime } from '../../common/enums';
 
 export class CreatePricingRuleDto {
   @ApiProperty({ enum: PricingResourceType })
@@ -20,11 +20,15 @@ export class CreatePricingRuleDto {
 }
 
 export class CreateServicePlanDto {
-  @ApiProperty({ example: 'Node.js Basic' })
+  @ApiProperty({ example: 'Node.js Standard' })
   @IsString()
   name: string;
 
-  @ApiPropertyOptional({ example: 'Basic plan for Node.js applications' })
+  @ApiProperty({ enum: AppRuntime, example: 'nodejs' })
+  @IsEnum(AppRuntime)
+  runtime: AppRuntime;
+
+  @ApiPropertyOptional({ example: 'Standard plan for Node.js applications' })
   @IsOptional()
   @IsString()
   description?: string;
@@ -46,6 +50,11 @@ export class UpdateServicePlanDto {
   @IsString()
   name?: string;
 
+  @ApiPropertyOptional({ enum: AppRuntime })
+  @IsOptional()
+  @IsEnum(AppRuntime)
+  runtime?: AppRuntime;
+
   @ApiPropertyOptional()
   @IsOptional()
   @IsString()