docs: streamline README — simplify structure, direct users to official website #498

Background

The README (both EN and ZH-CN) contains many sections that duplicate content already on the official documentation site at justerzhu.cn. This makes the README bloated and harder to maintain across languages.

Proposed Changes

• Remove: Supported Features, Infrastructure, Quick Start, Supported Frameworks, Operating Systems, AI Wiki, Contact us
• Replace GeneralSpacestation Product Introduction with 🚀 Official Website link to justerzhu.cn
• Update banner text to reference the website instead of the now-removed bottom contact section
• Apply consistently to both EN and ZH-CN versions

Related PR

• docs: streamline README — simplify structure, direct users to official website #497