feat(subscription): add common fields

Author: igdev0

packages/backend/src/subscription/entities/subscription.entity.ts

@@ -1,7 +1,34 @@
-import { Entity, PrimaryGeneratedColumn } from 'typeorm';
+import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
 
 @Entity('subscription')
 export default class SubscriptionEntity {
   @PrimaryGeneratedColumn()
-  id: string;
+  id: number;
+
+  @Column({ type: 'varchar', length: 42 }) // Ethereum address
+  subscriber: string;
+
+  @Column({ type: 'varchar', length: 42 }) // ERC20 token address
+  token: string;
+
+  @Column({ type: 'decimal', precision: 78, scale: 0 }) // BigNumber safe
+  amount: string;
+
+  @Column({ type: 'bigint' })
+  nextPaymentTime: string; // unix timestamp
+
+  @Column({ type: 'bigint' })
+  interval: string; // seconds
+
+  @Column({ type: 'int' })
+  poolId: number;
+
+  @Column({ type: 'smallint', unsigned: true })
+  remainingDuration: number;
+
+  @Column({ type: 'boolean', default: true })
+  active: boolean;
+
+  @Column({ type: 'bigint', nullable: true })
+  expiredAt: string | null;
 }