Refactor configuration and key management

- Removed key management configuration from .env.example and related code.
- Updated Makefile to load environment variables for HOST and PORT.
- Modified main.go to handle request logging with a wait group for graceful shutdown.
- Simplified dashboard statistics handler to focus on key counts and request metrics.
- Removed key manager implementation and related interfaces.
- Updated proxy server to use atomic counters for round-robin key selection.
- Cleaned up unused types and configurations in types.go.
- Added package-lock.json for frontend dependencies.

.env.example

@@ -11,21 +11,6 @@ PORT=3000
 # 服务器主机地址
 HOST=0.0.0.0
 
-# ===========================================
-# 密钥管理配置
-# ===========================================
-# 密钥文件路径
-KEYS_FILE=keys.txt
-
-# 起始密钥索引
-START_INDEX=0
-
-# 黑名单阈值（错误多少次后拉黑密钥）
-BLACKLIST_THRESHOLD=1
-
-# 最大重试次数（换key重试）
-MAX_RETRIES=3
-
 # ===========================================
 # OpenAI 兼容 API 配置
 # ===========================================
@@ -63,7 +48,7 @@ LOG_ENABLE_REQUEST=true
 # 认证配置
 # ===========================================
 # 项目认证密钥（可选，如果设置则启用认证）
-# AUTH_KEY=your-secret-key
+AUTH_KEY=sk-123456
 
 # ===========================================
 # CORS 配置