feat: AI聊天室多Agent协作讨论平台

- 实现Agent管理，支持AI辅助生成系统提示词
- 支持多个AI提供商（OpenRouter、智谱、MiniMax等）
- 实现聊天室和讨论引擎
- WebSocket实时消息推送
- 前端使用React + Ant Design
- 后端使用FastAPI + MongoDB

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/config.py

@@ -0,0 +1,50 @@
+"""
+应用配置模块
+从环境变量加载配置项
+"""
+from pydantic_settings import BaseSettings
+from typing import Optional
+
+
+class Settings(BaseSettings):
+    """应用配置类"""
+    
+    # MongoDB配置
+    MONGODB_URL: str = "mongodb://localhost:27017"
+    MONGODB_DB: str = "ai_chatroom"
+    
+    # 服务配置
+    HOST: str = "0.0.0.0"
+    PORT: int = 8000
+    DEBUG: bool = True
+    
+    # 安全配置
+    SECRET_KEY: str = "your-secret-key-change-in-production"
+    ENCRYPTION_KEY: str = "your-encryption-key-32-bytes-long"
+    
+    # CORS配置
+    CORS_ORIGINS: list = ["http://localhost:3000", "http://127.0.0.1:3000"]
+    
+    # WebSocket配置
+    WS_HEARTBEAT_INTERVAL: int = 30
+    
+    # 默认AI配置
+    DEFAULT_TIMEOUT: int = 60
+    DEFAULT_MAX_TOKENS: int = 2000
+    DEFAULT_TEMPERATURE: float = 0.7
+    
+    # 代理配置（全局默认）
+    DEFAULT_HTTP_PROXY: Optional[str] = None
+    DEFAULT_HTTPS_PROXY: Optional[str] = None
+    
+    # 速率限制
+    RATE_LIMIT_REQUESTS: int = 100
+    RATE_LIMIT_PERIOD: int = 60  # 秒
+    
+    class Config:
+        env_file = ".env"
+        env_file_encoding = "utf-8"
+
+
+# 全局配置实例
+settings = Settings()