docs: add FAQ section for common questions

[meichuanyi]

Summary

Add a comprehensive FAQ section to the README to help new users quickly find answers to common questions about Integuru.

Changes

• Added FAQ section covering:
  • General: What is Integuru, how it works, supported models
  • Setup & Configuration: System requirements, installation steps, API key setup
  • Usage: Capturing browser requests, HAR files, code generation, input variables
  • Troubleshooting: Graph generation failures, code generation errors, 2FA issues, Poetry problems

Motivation

New users often have the same questions about setup, how the agent works, and how to use the tool effectively. A well-structured FAQ section reduces friction and helps users get started faster.

Checklist

• Content is original and tailored to Integuru's features
• FAQ covers the most common user questions based on README content
• Troubleshooting section addresses practical issues
• Follows the project's contributing guidelines

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[meichuanyi]

@maintainer 请问有空 review 这个 FAQ 文档 PR 吗？感谢！

[meichuanyi]

@maintainer 请问有空 review 这个 FAQ 文档 PR 吗？如有需要修改的地方请告诉我 🙏