Use PostgreSQL as the only database backend across runtime, schema tooling, installation, Compose, and CI. Update regression tests and reject removed drivers explicitly.
Align MySQL and SQLite schemas, migrations, usage, stats, export, and backfill behavior with the shared data contracts. Extend gateway startup and maintenance support across all SQL drivers.
Shard and singleflight hot-path caches, batch and prioritize candidate and usage lifecycle persistence, and extend database and pressure-test instrumentation for 20k concurrent streams.
Introduce aether-data-schema and driver-specific schema generation for Postgres, MySQL, and SQLite.
Split data backends, lifecycle, repositories, and gateway runtime integration across database drivers.
Verified with cargo fmt --all --check, cargo clippy --workspace --all-targets -- -D warnings, and cargo test --workspace.