Simplify and Enhance Getting Started Documentation

[pattan]

The documentation has been enhanced to make the "Getting Started" experience significantly simpler and more intuitive.

Key improvements:

1. Redesigned Docs Homepage: Introduced a visual decision tree using a card-based layout to guide users based on their role: Publisher (AdOps), Publisher (Developer), or Creative.
2. Simplified Publisher Tutorial: Added a 2-step CDN-based "Quick Start" for immediate integration, while moving complex NPM/TypeScript setup to an "Advanced" section.
3. Streamlined Creative Tutorial: Lead with a copy-pasteable script tag example and clarified the "Why" behind the Advantage messaging protocol.
4. Improved Terminology: Updated core concept pages (Wrapper, Creative) with simpler analogies to reduce technical barriers for new users.
5. Direct Navigation: Changed the main site's "Get started" button to link directly to the new documentation entry point.

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PR created automatically by Jules for task 3262718192248018860 started by @pattan

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