docs: update website URL to cached-middleware-fetch-next.dev and bump version

[Copilot]

Updates the package website URL from the GitHub README to the new official website at https://cached-middleware-fetch-next.dev/.

Changes Made

Package Metadata

• Updated homepage field in package.json to point to the new official website
• Version bumped from 0.6.3 to 0.6.4 to ensure the updated metadata gets published to npm

Documentation

• Added prominent website link in README.md header section for better discoverability
• Positioned the website link right after the project description for maximum visibility

Before

"homepage": "https://github.com/bookernath/cached-middleware-fetch-next#readme"

After

"homepage": "https://cached-middleware-fetch-next.dev/"

The README now includes:

🌐 **[Official Website](https://cached-middleware-fetch-next.dev/)** | [![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/bookernath/cached-middleware-fetch-next)

Impact

• npm package page will now show the official website instead of GitHub README
• Users will have direct access to the dedicated documentation site
• Better user experience with proper website branding
• The version bump ensures these changes are reflected in the next npm publish

All tests pass and the package builds successfully with the new version.

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