//! # paladin-notifications
//!
//! Notification adapter implementations for the Paladin multi-agent framework.
//!
//! ## Feature flags
//!
//! | Flag | Enables |
//! |----------|---------|
//! | `email` | [`email_notification_adapter`] — requires `lettre` + `handlebars` |
//! | `push` | [`push_notification_adapter`] (stub, no extra deps) |
//! | `system` | [`system_notification_adapter`] — in-memory system notifications |
/// Email notification adapter (SMTP via `lettre`, templating via `handlebars`).
/// Push notification adapter (stub, no runtime dependencies).
/// System (in-app) notification adapter backed by in-memory storage.