FEAT-4: pedigree data module - depth-limited ancestor traversal, lazy expand, cycle guard, rd3t conversion (15 tests)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gerbil-manager-web/src/api/litters.ts

@@ -0,0 +1,7 @@
+/** Typed API functions for the Würfe (litters) resource. */
+import { api, resources } from './client'
+import type { Litter } from './types'
+
+export function getLitter(id: string): Promise<Litter> {
+  return api.get<Litter>(`${resources.litters}/${id}`)
+}