feat: default web API calls to same origin

apps/web/src/lib/api-base.ts

@@ -0,0 +1,22 @@
+const LOCALHOST_API_ORIGIN = 'http://localhost:3001';
+
+function trimTrailingSlashes(value: string): string {
+  return value.replace(/\/+$/, '');
+}
+
+export function getApiBaseUrl(
+  configuredApiBaseUrl?: string,
+  windowOrigin?: string,
+): string {
+  const configured = configuredApiBaseUrl?.trim();
+  if (configured) {
+    return trimTrailingSlashes(configured);
+  }
+
+  const origin = windowOrigin?.trim();
+  if (origin) {
+    return trimTrailingSlashes(origin);
+  }
+
+  return LOCALHOST_API_ORIGIN;
+}