feat(courseware,docs): 完善课件传输与岛编辑并统一全仓文档

- 增加课件上传、班级可见范围、设备补收与传输进度
- 整合自定义灵动岛编辑器和相关客户端交互
- 同步三端契约、数据库迁移、部署配置与隔离回归
- 按源码统一文档与官网说明，移除过时任务书和审查记录
- 保持产品版本为 1.4.0

packages/desktop-client/src/main/client-agent.ts

@@ -1,3 +1,4 @@
+import { pollCourseware } from './courseware.js';
 import { spawn } from 'node:child_process';
 import os from 'node:os';
 import fs from 'node:fs';
@@ -206,6 +207,7 @@ async function beat(): Promise<void> {
     if (!envelope.success || !envelope.data?.deviceId) throw new Error('心跳响应格式不正确');
     if (epoch !== connectionEpoch) return;
     const payload = envelope.data;
+    void pollCourseware();
     state.lastHeartbeatAt = new Date().toISOString();
     state.lastError = '';
     state.updateTargetVersion = payload.updateTargetVersion?.trim() ?? '';