[DX-241] Template landing pages component

[lfsigreja]

Related issue: DX-241 Add Fragment slot content structure to template files

Changes

This PR adds Fragment slot content structure to template showcase files across multiple frameworks:

• Angular templates: Added Fragment slot structure to angular-boilerplate, angular-buttercms, and angular-sanity templates
• Astro templates: Updated all Astro template showcase files (30+ templates) with Fragment slot content structure
• Gatsby templates: Added Fragment slot structure to gatsby-blog, gatsby-boilerplate, gatsby-ecommerce, and gatsby-butter-starter templates
• Next.js templates: Updated all Next.js template showcase files with Fragment slot content structure
• React templates: Added Fragment slot structure to react-boilerplate and butter-react-starter templates
• Portuguese translations: Updated all corresponding Portuguese (pt-br) template showcase files to maintain consistency

The changes ensure consistent content structure across all template showcase pages, improving the user experience and maintainability of the documentation.

Additional links

• Related to azion-webkit changes: ContentSection component updates with hasContainer prop