Multi-language README (de, zh, ja)

[keysersoft]

The website ships in seven languages; the README ships in one. The comparable projects that grow fastest all carry a language switcher at the top of the README.

What to do

• README.de.md, README.zh-CN.md, README.ja.md, with a language row directly under the H1 in each.
• Translate the prose, not the code blocks, the tool names or the licence text.
• German first: it is the market this project is strongest in and the one where no competitor has any German-language presence.

Please claim a language in a comment before starting so two people don't translate the same file.

[mrfandu1]

I’ll take German, Simplified Chinese, and Japanese, starting with German. I’ll preserve the code blocks, tool names, and licence text, and add the language row beneath the H1 in each README.

This will be an AI-assisted contribution for Chandan, with each translation checked against the English source. I’ll link the pull request here when it is ready.