Fix per-isolate GraphQL schema cache never invalidating across isolates
after runtime DDL: shared D1 schema_version counter bumped on every schema
mutation, version-aware self-invalidating caches (schema, fast-path metadata,
custom-query metadata) with a 3s TTL. QoL: delete_record takes a recordIds
array; friendlier MCP validation errors.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>