feat: add loading skeletons to catalog listing pages

[ulises-jeremias]

Describe the feature

Skeleton placeholders while catalog loads.

Use Case

Blank flash looks broken on slow networks.

Proposed Solution

Match final layout without inventing heavy cards.

Other Information

Maintainer-seeded Hacktoberfest issue for Create-Vlang-App website.

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

Version used

website @ main

Environment details (OS name and version, etc.)

n/a