refactor: config 路径自动检测 + 日志规范化 + me flag 过滤

[NeverENG]

Summary

• 新增 defaultLogDir() — 从当前目录向上查找 go.mod 来定位项目根目录，自动推导 log/ 路径
• WALPath / SSTablePath 改为基于自动检测的目录，不再硬编码 ../../../log
• 新增 meFlagArgs() — 从 os.Args 中仅提取 -me / -me=... 参数，避免未定义 flag 报错
• 所有日志改为结构化 slog 格式（无 [INFO] 等冗余前缀）
• ParseFlags 中无效 me 值改为 panic（替代 os.Exit），便于定位调用栈

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Configuration system now gracefully handles file reading and parsing failures by reverting to defaults, preventing unexpected termination
  • Enhanced validation and structured logging of configuration parameters during initialization
  • Improved diagnostic output to aid troubleshooting of configuration discovery and startup processes

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: edd91289-6f85-4efc-9ae0-b1c851878c08

📥 Commits

Reviewing files that changed from the base of the PR and between 4aada05 and aab7de6.

📒 Files selected for processing (1)

• config/global.go

---

📝 Walkthrough

Walkthrough

This PR refactors global configuration initialization and CLI argument parsing in config/global.go. It introduces dynamic log directory discovery, improves error handling to be more resilient, adds structured logging to key initialization steps, and implements selective flag parsing for the -me argument with stricter validation.

Changes

Configuration and CLI updates

Layer / File(s)	Summary
Log directory discovery infrastructure config/global.go (imports, defaultLogDir() helper)	Import statements add path/filepath and strings. New unexported defaultLogDir() helper searches upward from the current working directory for go.mod to determine the log directory, falling back to "log" if not found.
Dynamic path configuration and initialization config/global.go (NewGlobalConfig(), GlobalConfig.Init())	NewGlobalConfig() derives WALPath and SSTablePath dynamically via the computed log directory using filepath.Join. GlobalConfig.Init() logs the discovered config path, gracefully returns on read/unmarshal errors instead of terminating, and emits a finalized "config initialized" message.
Flag parsing with selective -me handling config/global.go (GlobalConfig.ParseFlags(), meFlagArgs() helper)	ParseFlags() now filters arguments to only parse -me and -me= flags via new unexported meFlagArgs() helper. Structured logging is added for me set by flag/environment and for final config state. Invalid me handling changes from os.Exit(1) to panic.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A rabbit hops through config with care,
Finding go.mod hiding here and there,
Flags parsed with grace, not exit but panic,
Error handling calm, not quite so manic,
Paths spring to life, dynamic and free!

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/config-improvements

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}