Support for pre-rendering individual svelte components (partial pre-rendering)

Describe the problem

Currently, how the rendering works is on page level, not on component level specific!
Sometimes, components such as Header, Footer or Sidebar are just needed to get re-rendered once during the time of build and never again!

Describe the proposed solution

With RSC we have cache, something similar to that maybe we can have

<script>
// from component file
export const prerender = true;
</script>
<header></header>

Alternatives considered

Alternative in front of me is to utilise the pre-render option at the page level

Importance

nice to have

Start by examining how prerendering currently works at the page level and how component files are handled. Compare the proposed component-level prerender = true and the mentioned cache-like approach, then define behavior for components such as headers, footers, and sidebars. Done should include a documented, tested design for partial prerendering.