- Upgrade fujiwara/raus from v0.2.0 to v0.3.0
- Enables slog integration support for Redis auto-assignment

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

- Replace stdlog with slog throughout main.go
- Integrate with raus v0.3.0 SetSlogLogger API
- Improve structured logging with key-value pairs
- Fix typo: "muset" -> "must" in worker-id flag description

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

- Pre-allocate buffer with estimated size to reduce allocations
- Add caching for source file paths using sync.Map
- Optimize common value types (string, int, bool, float64) formatting
- Optimize common log levels with direct string literals
- Use strconv.AppendInt/AppendFloat for better performance
- Add io.Writer field and sync.Map cache to customHandler struct

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

- Expand CLAUDE.md with comprehensive project architecture overview
- Document multi-protocol support and auto worker ID assignment
- Add detailed build & deployment options and tools
- Include development practices for code patterns and testing
- Document dependencies and their purposes

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Improve logging performance and consistency

Release for v2.2.1