fix(website): cache GitHub stars on server and show in nav (#734)

* fix(website): cache GitHub stars on server for 3 hours

Move star count fetching from universal +layout.ts to server-only code
so the GitHub API is not called on every page load or client navigation.

Add an in-memory cache with a 3-hour TTL and in-flight request
deduplication. On API errors (including rate limits), return the last
successful value when available.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(website): forward GitHub stars from server load to layout

Universal +layout.ts was shadowing +layout.server.ts data, so stars
never reached +layout.svelte and the nav rendered an empty span.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

---------
Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

apps/website/src/routes/+layout.ts

@@ -2,8 +2,9 @@ import type { MetaTagsProps } from 'svelte-meta-tags';
 
 export const prerender = true;
 
-export async function load({ url }) {
+export async function load({ data, url }) {
   return {
+    stars: data.stars,
     baseMetaTags: getBaseMetaTags(url),
     url: url.pathname
   };