feat: 实现 KPL 系统功能改进计划

1. 课程学习进度追踪
   - 新增 UserCourseProgress 和 UserMaterialProgress 模型
   - 新增 /api/v1/progress/* 进度追踪 API
   - 更新 admin.py 使用真实课程完成率数据

2. 路由权限检查完善
   - 新增前端 permissionChecker.ts 权限检查工具
   - 更新 router/guard.ts 实现团队和课程权限验证
   - 新增后端 permission_service.py

3. AI 陪练音频转文本
   - 新增 speech_recognition.py 语音识别服务
   - 新增 /api/v1/speech/* API
   - 更新 ai-practice-coze.vue 支持语音输入

4. 双人对练报告生成
   - 更新 practice_room_service.py 添加报告生成功能
   - 新增 /rooms/{room_code}/report API
   - 更新 duo-practice-report.vue 调用真实 API

5. 学习提醒推送
   - 新增 notification_service.py 通知服务
   - 新增 scheduler_service.py 定时任务服务
   - 支持钉钉、企微、站内消息推送

6. 智能学习推荐
   - 新增 recommendation_service.py 推荐服务
   - 新增 /api/v1/recommendations/* API
   - 支持错题、能力、进度、热门多维度推荐

7. 安全问题修复
   - DEBUG 默认值改为 False
   - 添加 SECRET_KEY 安全警告
   - 新增 check_security_settings() 检查函数

8. 证书 PDF 生成
   - 更新 certificate_service.py 添加 PDF 生成
   - 添加 weasyprint、Pillow、qrcode 依赖
   - 更新下载 API 支持 PDF 和 PNG 格式

backend/app/api/v1/endpoints/speech.py

@@ -0,0 +1,145 @@
+"""
+语音识别 API
+"""
+from typing import Optional
+from fastapi import APIRouter, Depends, File, UploadFile, Form, HTTPException
+from pydantic import BaseModel
+
+from app.core.database import get_db
+from app.api.deps import get_current_user
+from app.models.user import User
+from app.services.speech_recognition import (
+    get_speech_recognition_service,
+    SpeechRecognitionError,
+)
+
+router = APIRouter()
+
+
+class SpeechRecognitionRequest(BaseModel):
+    """语音识别请求（文本形式）"""
+    text: str
+    session_id: Optional[int] = None
+
+
+class SpeechRecognitionResponse(BaseModel):
+    """语音识别响应"""
+    code: int = 200
+    message: str = "识别成功"
+    data: dict
+
+
+@router.post("/recognize/text", response_model=SpeechRecognitionResponse)
+async def recognize_text(
+    request: SpeechRecognitionRequest,
+    current_user: User = Depends(get_current_user),
+):
+    """
+    处理前端已识别的语音文本
+    用于 Web Speech API 识别后的文本传输
+    """
+    service = get_speech_recognition_service("simple")
+    
+    try:
+        text = await service.recognize_text(request.text)
+        return SpeechRecognitionResponse(
+            code=200,
+            message="识别成功",
+            data={
+                "text": text,
+                "session_id": request.session_id,
+            }
+        )
+    except SpeechRecognitionError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+
+
+@router.post("/recognize/audio", response_model=SpeechRecognitionResponse)
+async def recognize_audio(
+    audio: UploadFile = File(...),
+    format: str = Form(default="wav"),
+    sample_rate: int = Form(default=16000),
+    engine: str = Form(default="aliyun"),
+    current_user: User = Depends(get_current_user),
+):
+    """
+    识别音频文件
+    
+    支持的音频格式：wav, pcm, mp3, ogg, opus
+    支持的识别引擎：aliyun, xunfei
+    """
+    # 读取音频数据
+    audio_data = await audio.read()
+    
+    if len(audio_data) == 0:
+        raise HTTPException(status_code=400, detail="音频文件为空")
+    
+    if len(audio_data) > 10 * 1024 * 1024:  # 10MB 限制
+        raise HTTPException(status_code=400, detail="音频文件过大，最大支持 10MB")
+    
+    service = get_speech_recognition_service(engine)
+    
+    try:
+        text = await service.recognize_audio(audio_data, format, sample_rate)
+        return SpeechRecognitionResponse(
+            code=200,
+            message="识别成功",
+            data={
+                "text": text,
+                "format": format,
+                "sample_rate": sample_rate,
+                "engine": engine,
+            }
+        )
+    except SpeechRecognitionError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    except NotImplementedError as e:
+        raise HTTPException(status_code=501, detail=str(e))
+
+
+@router.get("/engines")
+async def get_available_engines(
+    current_user: User = Depends(get_current_user),
+):
+    """
+    获取可用的语音识别引擎列表
+    """
+    import os
+    
+    engines = [
+        {
+            "id": "simple",
+            "name": "浏览器语音识别",
+            "description": "使用浏览器内置的 Web Speech API 进行语音识别",
+            "available": True,
+        },
+        {
+            "id": "aliyun",
+            "name": "阿里云智能语音",
+            "description": "使用阿里云 NLS 服务进行高精度语音识别",
+            "available": all([
+                os.getenv("ALIYUN_ACCESS_KEY_ID"),
+                os.getenv("ALIYUN_ACCESS_KEY_SECRET"),
+                os.getenv("ALIYUN_NLS_APP_KEY"),
+            ]),
+        },
+        {
+            "id": "xunfei",
+            "name": "讯飞语音识别",
+            "description": "使用讯飞 IAT 服务进行语音识别",
+            "available": all([
+                os.getenv("XUNFEI_APP_ID"),
+                os.getenv("XUNFEI_API_KEY"),
+                os.getenv("XUNFEI_API_SECRET"),
+            ]),
+        },
+    ]
+    
+    return {
+        "code": 200,
+        "message": "获取成功",
+        "data": {
+            "engines": engines,
+            "default": "simple",
+        }
+    }