Fix calculator loader URL for SSR

hdyc-svelte/src/lib/data/calculatorLoader.ts

@@ -17,11 +17,21 @@ export interface CalculatorDef {
 let cache: CalculatorDef[] | null = null;
 let pending: Promise<CalculatorDef[]> | null = null;
 
+const runtimeHost =
+  import.meta.env.PUBLIC_SITE_URL ??
+  (import.meta.env.DEV ? 'http://localhost:5173' : 'https://howdoyouconvert.com');
+
+const getCalculatorsUrl = (): string =>
+  import.meta.env.SSR
+    ? new URL('/data/calculators.json', runtimeHost).toString()
+    : '/data/calculators.json';
+
 export async function loadCalculators(): Promise<CalculatorDef[]> {
   if (cache) return cache;
   if (pending) return pending;
 
-  pending = fetch('/data/calculators.json')
+  const url = getCalculatorsUrl();
+  pending = fetch(url)
     .then(r => r.json())
     .then((data: CalculatorDef[]) => {
       cache = data;