docs(readme): improve clarity and add security guidance

[KemingHe]

CHANGES

• Clarify problem statement with concrete AI command examples
• Add Docker commit hash pinning for production security
• Remove redundant sections and sync across README files
• Convert diagrams to mobile-friendly lists in dockerhub version

IMPACT

• Users better understand when to use this tool vs alternatives
• Production deployments can audit container contents for security
• Consistent messaging across GitHub and Docker Hub

[Copilot]

Pull Request Overview

This PR improves documentation clarity and adds security guidance to README files. The changes make the tool's purpose clearer to users and introduce security best practices for production deployments.

• Enhanced problem statement with specific AI command examples
• Added Docker commit hash pinning guidance for production security
• Streamlined documentation by removing redundant content and converting diagrams to mobile-friendly format

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
README.md	Updated problem statement, added security guidance for Docker pulls, and removed redundant maintenance section
README-dockerhub.md	Applied same clarity improvements and converted diagram to mobile-friendly list format