Add Logging and Monitoring Support

[FerdinandSu]

Description / 描述

English:
Improve logging and add structured logging support:

• Implement structured logging with Serilog
• Add request/response logging middleware
• Log important business events
• Support different log outputs (Console, File, Seq, etc.)
• Add correlation IDs for request tracking

中文:
改进日志记录并添加结构化日志支持：

• 使用 Serilog 实现结构化日志
• 添加请求/响应日志中间件
• 记录重要的业务事件
• 支持不同的日志输出（控制台、文件、Seq 等）
• 添加请求跟踪的关联 ID

Difficulty / 难度

Medium / 中等

Estimated Time / 预计时间

4-6 hours

Acceptance Criteria / 验收标准

• Install Serilog packages
• Configure Serilog in Program.cs
• Add request logging middleware
• Add logging to all managers and controllers
• Support configuration via environment variables
• Add documentation for logging configuration
• Test different log outputs

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