Added Ecomail contact sync: contacts are automatically subscribed and
tagged on the configured mailing list when a customer signs up or an order
is fulfilled, with tags for sign-up, purchase, high-value orders, and
purchased product categories.
Fixed missing dashboard module descriptions on the Ecomail CP dashboard.
Initial plugin bootstrap: Composer scaffold, CP navigation, settings (API
key), and the Ecomail API client service (lists, subscribers,
transactional email).
Added the CP dashboard: connection status, mailing list count, and a
per-list subscriber overview.