In-memory aa-storage driver.

DashMap- and parking_lot-backed implementations of the six storage traits, for unit/integration tests and local development without a real database. State is ephemeral — it lives only for the life of the process.

Driver registration

Call [register] from boot code to announce all six backends to an [aa_storage::Registry] under [DRIVER_NAME] ("memory"), so an agent-assembly.toml [storage] section can select them by name. The per-kind [factory] types build a store from its [storage.memory] subsection (which the memory driver ignores — it needs no connection settings).