Description

This Pull Request introduces the official Simplified Chinese translation of the README (README.zh.md) for Crawl4AI.

Motivation
Crawl4AI is the most starred open-source web crawler designed for LLMs and RAG pipelines. As its adoption among Chinese developers and AI researchers surges, providing a high-quality, manually verified Chinese README is essential. This localization will help users better understand core features like LLM-friendly Markdown generation, structured data extraction, and Docker-based self-hosting, further expanding the project's global impact.

Changes Made

• Created README.zh.md with a full, high-quality manual translation of the latest README.md.
• Added a language switcher at the top of both README.md and README.zh.md for seamless navigation.
• Ensured strict structural parity with the original document, including all headings, code examples (CLI/Python), and sponsorship details.
• Accurately translated technical terminology (e.g., "RAG", "LLM-Driven Extraction", "Managed Browser", "Stealth Mode").
• Preserved all original HTML badges, links, and layout elements for consistent visual identity.

Validation

• Validated markdown and HTML syntax.
• Manually checked parity against the current main branch.

Thank you for building such a game-changing tool for the AI era! I'm excited to help the Chinese community discover and contribute to Crawl4AI.