Multi-language (language files)

All user-visible text is read from readwithhotsoup/languages/<code>.json. The source-of-truth strings are English; a language file is "English key → translation", falling back to the English original when missing. Files support nested group structures (Lang.Init flattens automatically, compatible with the old flat format).

• Selection order: --lang <code> argument > LANG environment variable > default zh-CN
• On first launch, default translations are auto-copied/merged into the data directory; edit the files there directly, changes take effect immediately
• New translation keys are auto-merged into existing files, without overwriting keys you've modified
• Custom translations: copy en-US.json to your-code.json, change the values, then load it with --lang your-code