SurrealDB 3.1: stability, DiskANN, and a new release process

SurrealDB 3.1, the first minor release in the 3.x series, introduces several enhancements, focusing on stability, security, and new features like the DiskANN approximate-nearest-neighbour index, which is suited for larger-than-memory vector workloads. The release also upgrades the GraphQL interface, aligning with Apollo conventions and adding features like cursor pagination and multi-model filtering, enhancing compatibility with modern GraphQL clients and supporting AI-native and analytics-heavy workloads. A significant improvement in in-memory performance is achieved through optimistic lock coupling, allowing lock-free access for readers. The update addresses various bug fixes and stability improvements from the 3.0 line, alongside security hardening through increased investment in LLM-assisted security review. Enterprise customers benefit from new operational tools like structured audit logs and a slow-query pipeline. SurrealDB 3.1 also marks a shift to a private development workflow, synchronizing public updates after releases to enhance security response times while maintaining community transparency through the public repository for issues and discussions.