[earsonlau]

What this changes

Adds README.zh-CN.md, a Simplified Chinese translation of the root README.md, so the
project is readable by Chinese-speaking contributors without changing any behaviour.

The translation covers every section of the English README: the product framing and
template-not-product notes, what it is, AG-UI, requirements, quick start, Intelligence on
your own machine, deploy, try it, main surfaces, features, bring your own agent,
configuration, architecture, sign in, organization sign-in for desktop installations,
keeping it to your machine, development, documentation, contributing and license.

It is a documentation-only change. No code, dependency, workflow, or configuration file
is touched, so the Where it runs, Boundary and audit, and Changelog sections of this
template do not apply. Adding a translated README is a reasonable follow-up to
#1218, the onboarding/entry-page work
that already assumed readers who do not read English comfortably.

How it was checked

• Section structure matches one-to-one: 19 ##/### headings in both files.
• All 62 table rows and all 30 unique environment variables from the English README are
  present.
• All 11 fenced code blocks are present in the same order. Commands are byte-identical to
  the English README; only inline comments inside shell blocks are translated.
• All 26 URLs resolve to the same targets as the English README.
• Every relative link target (docs/*, charts/openbot/README.md, prompt.txt,
  ./LICENSE, README.md) exists in the repository.
• Line endings are LF, matching .gitattributes (* text=auto eol=lf). No trailing
  whitespace (git diff --cached --check clean).
• Markdown renders correctly: HTML <div>, <picture>, <source> and <img> blocks are
  balanced, code fences are paired, and internal anchors point at real headings.
• No secrets, credentials, customer data, or local paths are included. All example values
  are the same placeholders the English README uses.

Notes for maintainers

• The file name follows the common README.<locale>.md convention. If the project prefers
  a different layout, such as docs/README.zh-CN.md, renaming is trivial.
• The English README was not modified, so there is no merge conflict risk. The translated
  copy adds a footer link back to README.md, and the header links to it, so readers can
  switch either way.
• biome.json does not cover Markdown, and ci.yml has no Markdown or link-check step,
  so no new check is required.
• OpenBot has no CONTRIBUTING.md. This PR follows the root README.md contributing
  rules: focused change, docs kept in step with setup and configuration, no secrets, and
  the Development checks were not needed because nothing executable changed.