chore: 初始化项目基础结构和资源文件

- 添加项目图标文件（app-icon.png、各平台图标）
- 配置开发环境文件（.env、.nvmrc、.npmrc）
- 添加静态资源文件（背景图片、字体、音频）
- 初始化Tauri后端结构（build.rs、main.rs、模块文件）
- 配置前端项目结构（TypeScript、Vue组件、样式）
- 添加Node.js API服务基础结构
- 配置构建和开发工具（vite、prettier、gitignore）

node_api/src/modules/meeting/meeting.service.ts

@@ -0,0 +1,108 @@
+import { Injectable } from '@nestjs/common';
+import { Role, RtcTokenBuilder } from '../../plugins/shengwang/RtcTokenBuilder2';
+import { NacosConfigService } from '../../plugins/nacos/nacos-config.service';
+import { EntityManager } from '@mikro-orm/core';
+import { MeetingUser } from './entities/meeting-user.entity';
+import type { TokenResponseDto } from './meeting.dto';
+
+@Injectable()
+export class MeetingService {
+  constructor(
+    private readonly em: EntityManager,
+    private readonly nacosConfig: NacosConfigService
+  ) {}
+
+  /**
+   * 通过作业 ID 查询老师的长 ID
+   * @param homeworkId - 作业 ID（JoinRoomData.homeworkId）
+   * @returns 老师长 ID，未查询到返回 null
+   */
+  public async getTeacherLongUserIdByHomeworkId(homeworkId: number): Promise<number | null> {
+    const id = Number(homeworkId);
+    if (!Number.isFinite(id) || id <= 0) {
+      return null;
+    }
+    const sql = 'SELECT B.TeacherId AS teacherId FROM icr_homework AS A LEFT JOIN scs_studentgroup AS B ON A.StudentGroupId = B.Id WHERE A.Id = ? LIMIT 1';
+    const rows = (await this.em.getConnection().execute(sql, [id])) as Array<{ teacherId?: number | string }>;
+    const teacherIdRaw = rows?.[0]?.teacherId;
+    const teacherId = teacherIdRaw === undefined ? NaN : Number(teacherIdRaw);
+    if (!Number.isFinite(teacherId) || teacherId <= 0) {
+      return null;
+    }
+    return teacherId;
+  }
+
+  /**
+   * 通过作业 ID 获取老师的短 UID
+   * @param homeworkId - 作业 ID（JoinRoomData.homeworkId）
+   * @returns 老师短 UID，未查询到返回 null
+   */
+  public async getTeacherShortUidByHomeworkId(homeworkId: number): Promise<number | null> {
+    const teacherLongUserId = await this.getTeacherLongUserIdByHomeworkId(homeworkId);
+    if (!teacherLongUserId) {
+      return null;
+    }
+    return await this.getOrAssignShortUid(teacherLongUserId);
+  }
+
+  /**
+   * 获取或分配用户的短 UID
+   * @param longUserId - 用户的真实 ID（bigint）
+   * @returns 分配的短 UID（数据库自增 ID）
+   */
+  public async getOrAssignShortUid(longUserId: number | string): Promise<number> {
+    const userId = typeof longUserId === 'string' ? BigInt(longUserId) : BigInt(longUserId);
+
+    // 尝试获取已存在的记录
+    const existingUser = await this.em.findOne(MeetingUser, { longUserId: Number(userId) });
+
+    if (existingUser) {
+      // 复用已有的短 UID
+      console.log(`[MeetingService] 用户 ${longUserId} 复用短 UID: ${existingUser.id}`);
+      return existingUser.id;
+    }
+
+    // 创建新记录（数据库自增 ID 会自动分配）
+    try {
+      const newUser = this.em.create(MeetingUser, { longUserId: Number(userId), createdAt: new Date() });
+      await this.em.flush();
+      console.log(`[MeetingService] 为用户 ${longUserId} 分配短 UID: ${newUser.id}`);
+      return newUser.id;
+    } catch (error: any) {
+      // 处理并发导致的唯一索引冲突 (MySQL Error 1062: Duplicate entry)
+      if (error.code === 'ER_DUP_ENTRY' || error.message?.includes('Duplicate entry')) {
+        console.warn(`[MeetingService] 检测到并发创建冲突，重新获取用户 ${longUserId}`);
+        this.em.clear(); // 清除当前上下文，防止缓存干扰
+        const retryUser = await this.em.findOne(MeetingUser, { longUserId: Number(userId) });
+        if (retryUser) {
+          return retryUser.id;
+        }
+      }
+      throw error;
+    }
+  }
+
+  public generateToken(channelName: string, uid: number): TokenResponseDto | null {
+    // 从 Nacos 配置获取 appId 和 appCertificate
+    const agoraConfig = this.nacosConfig.getDefaultAgoraAppConfig();
+    const now = Date.now();
+    const role = Role.PUBLISHER;
+    const tokenExpirationInSecond = 60 * 60 * 24; // 24 小时
+    const privilegeExpirationInSecond = tokenExpirationInSecond;
+    const token = RtcTokenBuilder.buildTokenWithUid(
+      agoraConfig.appId,
+      agoraConfig.appCertificate,
+      channelName, // 使用清理后的频道名
+      uid,
+      role,
+      tokenExpirationInSecond,
+      privilegeExpirationInSecond
+    );
+
+    if (!token) {
+      return null;
+    }
+    const expiresAt = now + tokenExpirationInSecond * 1000;
+    return { appid: agoraConfig.appId, rtcToken: token, expiresAt };
+  }
+}