Remove dumi-based website infrastructure

[Copilot]

New official website built in site/ directory using Next.js. Removing old dumi-based documentation system.

Changes

Removed files:

• .dumirc.ts - dumi configuration
• docs/ - legacy documentation directory
• mako.config.json - dumi build config
• .github/workflows/deploy-site.yml - old deployment workflow

Updated package.json:

• Removed scripts: start, dev, docs:build, docs:build-analyze, docs:deploy, deploy
• Removed dependencies: dumi, gh-pages

Updated .gitignore:

• Removed docs-dist, .dumi entries

Original prompt

已经构建了新官网放在了 site 目录中。旧的官网站点需要删除，我知道的就是 dumi 相关，docs 目录。其他有相关的你可以看看。

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Latest commit: f9beac4

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