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

SurrealDB 3.1, the first 3.x minor release, adds DiskANN for approximate nearest-neighbor search alongside HNSW.

GraphQL support is broader, with aliases and cursor pagination now included.

In-memory datastore performance is improved, with faster reads and related optimizations.

The release also bundles extensive bug fixes, security hardening, and a new development/release process.