TTL-based list response caching

You can now cache listRows responses by passing a ttl parameter (in seconds). The first request executes normally and stores the result in an in-memory cache. Subsequent identical requests return the cached response instantly until the TTL expires. The cache is permission-aware, so users with different roles never see each other's cached data.

Set ttl between 1 and 86400 (24 hours). The default is 0 (caching disabled). Row writes do not invalidate the cache. To force a purge, call updateTable with purge set to true.