Refactor Dockerfile to use Poetry consistently

[luojiyin1987]

• Replace uv/pip mixed usage with unified Poetry approach
• Optimize layer caching by copying pyproject.toml and README.md first
• Fix dependency installation order (--no-root then --only-root)
• Add dev dependencies section to pyproject.toml for better separation
• Move pytest, pytest-asyncio, and pre-commit to dev dependencies

This resolves build failures caused by package source availability and lock file synchronization issues.

🤖 Generated with Claude Code

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