[Enhancement] Strengthen README positioning around offline support and differentiation

[sonukapoor]

Summary

Improve the README again so offline advisory DB support is positioned as a core differentiator, not just an additional feature.

Why

Offline support is one of the strongest capabilities in the project right now. It materially improves adoption potential in enterprise, restricted-network, and security-conscious environments.

To maximize adoption and communicate the product value clearly, the README should make that advantage more visible in the top-level messaging and in comparisons with similar tools.

Goals

• strengthen the top-of-README value proposition around offline support
• explain why zero-runtime-network scanning matters in practice
• make offline support more visible in the comparison section
• add clearer differentiation for enterprise and restricted-environment usage
• reduce confusion between sync, online scan, and offline scan workflows

Possible improvements

• revise the hero and intro copy to mention offline support earlier
• add a short section explaining why offline mode matters
• add offline support to the comparison table
• strengthen the enterprise and restricted-environment use cases
• make the workflow distinction between sync and scan clearer
• make offline support more prominent in the standout section

Expected outcome

• stronger product positioning
• clearer differentiation from similar tools
• better adoption story for developers, enterprises, and reviewers
• a README that better reflects one of the project’s biggest recent wins