api: GET /api/world + POST /api/jump, OpenAPI spec updated in code

app/api/world/route.ts

@@ -0,0 +1,8 @@
+import { getGameDb } from '@/lib/db/client'
+import { getWorldState } from '@/lib/game/save'
+
+// The full world state for the single active save; auto-initializes on first hit.
+export async function GET() {
+  const db = await getGameDb()
+  return Response.json(await getWorldState(db))
+}