refactor: 移除高优先级投标功能及相关代码

src/bids/entities/bid-item.entity.ts

@@ -17,15 +17,6 @@ export class BidItem {
   @Column()
   source: string;
 
-  @Column({ default: false })
-  isRead: boolean;
-
-  @Column({ default: 0 })
-  priority: number;
-
-  @Column({ nullable: true })
-  unit: string;
-
   @CreateDateColumn()
   createdAt: Date;