Sequential consistency without borders: How D1 implements global read replication

Introduces D1 read replication and the new Sessions API. The Sessions API enables sequential consistency for queries within a session, even when routed to different replicas. It uses bookmarks to maintain session state across requests, ensuring properties like 'read my own writes' and 'writes follow reads'. The post details the implementation of sessions, bookmarking, and the benefits for read-heavy applications.