Optimization of fetching products in `featured-collection.liquid`

[LA1CH3]

Describe the enhancement you'd like

When the featured collection section renders, it should reuse the products it already fetched and stop preloading products that never appear, so large collections load fast and no longer risk timing out. No real drawbacks—behavior stays the same but render cost matches the number of cards shown.

We have found that shops with many complex products (high variant count, high location counts, etc.) can experience slowness and timeouts when fetching products in the featured collection.

Describe alternatives you've considered

Looked at reducing the default product count and adding pagination, but both change the merchant experience; the caching-and-loop tweak fixes the slowdown without altering layout or settings.

Additional context/screenshots