test(geschichten): add failing tests for draft fetch in page loader

RED: loader does not yet call parent() or fetch DRAFT stories.
Also extracts settled<T>() helper to $lib/shared/server/settled.ts
and seeds makeData/callLoad factories with drafts/parent defaults.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/shared/server/settled.ts

@@ -0,0 +1,5 @@
+export function settled<T>(res: PromiseSettledResult<unknown> | undefined): T | null {
+	if (res?.status !== 'fulfilled') return null;
+	const v = res.value as { response: Response; data: unknown };
+	return v.response.ok ? ((v.data as T) ?? null) : null;
+}