新增AI教练模块，包括控制器、服务、模型及数据传输对象，更新应用模块以引入新模块，同时在打卡模块中添加按时间范围返回每日打卡状态的功能

src/ai-coach/ai-coach.service.ts

@@ -0,0 +1,110 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { OpenAI } from 'openai';
+import { Readable } from 'stream';
+import { AiMessage, RoleType } from './models/ai-message.model';
+
+const SYSTEM_PROMPT = `你是一位资深的普拉提与运动康复教练（Pilates Coach），具备运动解剖学、体态评估、疼痛预防、功能性训练、力量与柔韧性、营养与饮食建议等专业知识。
+请遵循以下规则作答：
+1) 话题范围仅限：健康、健身、普拉提、康复、形体训练、柔韧性、力量训练、运动损伤预防与恢复、营养与饮食。
+2) 拒绝回答医疗诊断、情感心理、时政金融、编程等不相关或高风险话题，礼貌解释并引导回合适范围。
+3) 语言风格：亲切、专业、简洁分点回答；必要时提供可在家执行的分步骤方案与注意事项；给出不同水平与疼痛人群的替代动作与安全提示。
+4) 强调循序渐进与个体差异，避免绝对化表述；涉及疼痛或既往伤病时，建议在医生评估后进行训练。
+5) 所有训练建议默认不需要器械或仅需常见小器械（瑜伽垫、弹力带、泡沫轴等），估算时长与频率，并提供跟踪与自测方法。`;
+
+@Injectable()
+export class AiCoachService {
+  private readonly logger = new Logger(AiCoachService.name);
+  private readonly client: OpenAI;
+  private readonly model: string;
+
+  constructor(private readonly configService: ConfigService) {
+    const dashScopeApiKey = this.configService.get<string>('DASHSCOPE_API_KEY') || '';
+    const baseURL = this.configService.get<string>('DASHSCOPE_BASE_URL') || 'https://dashscope.aliyuncs.com/compatible-mode/v1';
+
+    this.client = new OpenAI({
+      apiKey: dashScopeApiKey,
+      baseURL,
+    });
+    // 默认选择通义千问对话模型（OpenAI兼容名），可通过环境覆盖
+    this.model = this.configService.get<string>('DASHSCOPE_MODEL') || 'qwen-plus';
+  }
+
+  async createOrAppendMessages(params: {
+    userId: string;
+    conversationId?: string;
+    userContent: string;
+  }): Promise<{ conversationId: string }> {
+    const conversationId = params.conversationId || `${params.userId}-${Date.now()}`;
+    await AiMessage.create({
+      conversationId,
+      userId: params.userId,
+      role: RoleType.User,
+      content: params.userContent,
+      metadata: null,
+    });
+    return { conversationId };
+  }
+
+  buildChatHistory = async (userId: string, conversationId: string) => {
+    const history = await AiMessage.findAll({
+      where: { userId, conversationId },
+      order: [['created_at', 'ASC']],
+    });
+
+    const messages = [
+      { role: 'system' as const, content: SYSTEM_PROMPT },
+      ...history.map((m) => ({ role: m.role as 'user' | 'assistant' | 'system', content: m.content })),
+    ];
+    return messages;
+  };
+
+  async streamChat(params: {
+    userId: string;
+    conversationId: string;
+    userContent: string;
+  }): Promise<Readable> {
+    // 上下文：系统提示 + 历史 + 当前用户消息
+    const messages = await this.buildChatHistory(params.userId, params.conversationId);
+
+    const stream = await this.client.chat.completions.create({
+      model: this.model,
+      messages,
+      stream: true,
+      temperature: 0.7,
+      max_tokens: 1024,
+    });
+
+    const readable = new Readable({ read() { } });
+    let assistantContent = '';
+
+    (async () => {
+      try {
+        for await (const chunk of stream) {
+          const delta = chunk.choices?.[0]?.delta?.content || '';
+          if (delta) {
+            assistantContent += delta;
+            readable.push(delta);
+          }
+        }
+        // 结束：将assistant消息入库
+        await AiMessage.create({
+          conversationId: params.conversationId,
+          userId: params.userId,
+          role: RoleType.Assistant,
+          content: assistantContent,
+          metadata: { model: this.model },
+        });
+      } catch (error) {
+        this.logger.error(`stream error: ${error?.message || error}`);
+        readable.push('\n[对话发生错误，请稍后重试]');
+      } finally {
+        readable.push(null);
+      }
+    })();
+
+    return readable;
+  }
+}
+
+