fix: resolve circular import errors in TypeORM entities

- Use string-based @OneToMany relations in parent entities (wallet, ticket, service-plan)
  to break circular import chains that confused VS Code TS language server
- Add .vscode/settings.json to suppress Tailwind CSS @tailwindcss unknownAtRules warnings
- Reorder imports in child entities for consistency

backend/src/billing/entities/pricing-rule.entity.ts

@@ -6,8 +6,8 @@ import {
   JoinColumn,
   CreateDateColumn,
 } from 'typeorm';
-import { PricingResourceType } from '../../common/enums';
 import { ServicePlan } from './service-plan.entity';
+import { PricingResourceType } from '../../common/enums';
 
 @Entity('pricing_rules')
 export class PricingRule {

backend/src/billing/entities/service-plan.entity.ts

@@ -7,7 +7,6 @@ import {
   OneToMany,
 } from 'typeorm';
 import { BillingCycle, AppRuntime } from '../../common/enums';
-import { PricingRule } from './pricing-rule.entity';
 
 @Entity('service_plans')
 export class ServicePlan {
@@ -29,8 +28,8 @@ export class ServicePlan {
   @Column({ default: true })
   isActive: boolean;
 
-  @OneToMany(() => PricingRule, (rule) => rule.plan, { cascade: true, eager: true })
-  pricingRules: PricingRule[];
+  @OneToMany('PricingRule', 'plan', { cascade: true, eager: true })
+  pricingRules: any[];
 
   @CreateDateColumn()
   createdAt: Date;

backend/src/billing/entities/wallet-transaction.entity.ts

@@ -6,8 +6,8 @@ import {
   JoinColumn,
   CreateDateColumn,
 } from 'typeorm';
-import { TransactionType } from '../../common/enums';
 import { Wallet } from './wallet.entity';
+import { TransactionType } from '../../common/enums';
 
 @Entity('wallet_transactions')
 export class WalletTransaction {

backend/src/billing/entities/wallet.entity.ts

@@ -9,7 +9,6 @@ import {
   OneToMany,
 } from 'typeorm';
 import { User } from '../../users/entities/user.entity';
-import { WalletTransaction } from './wallet-transaction.entity';
 
 @Entity('wallets')
 export class Wallet {
@@ -26,8 +25,8 @@ export class Wallet {
   @Column({ unique: true })
   userId: string;
 
-  @OneToMany(() => WalletTransaction, (tx: WalletTransaction) => tx.wallet)
-  transactions: WalletTransaction[];
+  @OneToMany('WalletTransaction', 'wallet')
+  transactions: any[];
 
   @CreateDateColumn()
   createdAt: Date;