feat: 新增目标子任务管理功能模块

- 实现目标子任务的完整功能，包括数据库表设计、API接口、业务逻辑和文档说明。
- 支持用户创建、管理和跟踪目标子任务，提供增删改查操作及任务完成记录功能。
- 引入惰性任务生成机制，优化任务管理体验，提升系统性能和用户交互。

src/goals/goals.module.ts

@@ -2,17 +2,19 @@ import { Module } from '@nestjs/common';
 import { SequelizeModule } from '@nestjs/sequelize';
 import { GoalsController } from './goals.controller';
 import { GoalsService } from './goals.service';
+import { GoalTaskService } from './services/goal-task.service';
 import { Goal } from './models/goal.model';
 import { GoalCompletion } from './models/goal-completion.model';
+import { GoalTask } from './models/goal-task.model';
 import { UsersModule } from '../users/users.module';
 
 @Module({
   imports: [
-    SequelizeModule.forFeature([Goal, GoalCompletion]),
+    SequelizeModule.forFeature([Goal, GoalCompletion, GoalTask]),
     UsersModule,
   ],
   controllers: [GoalsController],
-  providers: [GoalsService],
-  exports: [GoalsService],
+  providers: [GoalsService, GoalTaskService],
+  exports: [GoalsService, GoalTaskService],
 })
-export class GoalsModule {}
+export class GoalsModule { }