Turso/libSQL async database driver for the rbdc database abstraction layer.

This crate provides an async Turso database backend for rbdc, using the libsql native async API as the underlying client library. It supports both remote Turso databases (with auth tokens) and local/in-memory databases.

Backend choice is fixed at initialization time. The application selects Turso by wiring TursoDriver during startup configuration.

• No runtime backend switching - the active backend cannot be changed while the application is serving traffic.
• No automatic fallback - if Turso becomes unavailable, requests fail rather than silently falling back.

Changes to backend selection take effect only after a deploy/restart cycle.

use rbdc_turso::{TursoDriver, TursoConnectOptions};
use rbdc::db::Driver;

// At startup: wire the Turso driver
let driver = TursoDriver {};

// In-memory (local, no network)
let mut conn = driver.connect("turso://:memory:").await?;

// Remote Turso database
let mut conn = driver.connect("turso://?url=libsql://your-db.turso.io&token=YOUR_TOKEN").await?;

// Local file database
let mut conn = driver.connect("turso://path/to/local.db").await?;

This crate implements the standard rbdc driver traits:

• rbdc::db::Driver - via TursoDriver
• rbdc::db::ConnectOptions - via TursoConnectOptions
• rbdc::db::Connection - via TursoConnection
• rbdc::db::Row - via TursoRow
• rbdc::db::MetaData - via TursoMetaData
• rbdc::db::Placeholder - via TursoDriver (uses ? placeholders)

For the full feature specification, parity requirements, and deviation governance process, see:

• kitty-specs/001-turso-backend-parity-rollout/spec.md
• kitty-specs/001-turso-backend-parity-rollout/plan.md