changelog.md for @social.io/social.io

Changelog

Add email subsystem: interfaces and models for accounts, folders, threads and messages; integrate smartimap plugin; update exports and documentation

Add comprehensive email interfaces (ts/interfaces/email.interfaces.ts) describing accounts, IMAP config, folders, threads, messages, drafts and realtime email events
Introduce Email models: EmailAccount, EmailFolder, EmailThread, Email with persistence helpers, safe-object serializers and helper methods (ts/models/email.account.ts, ts/models/email.folder.ts, ts/models/email.thread.ts, ts/models/email.ts)
Integrate smartimap into centralized plugins (ts/plugins.ts) and export it for use by email functionality
Export email models from models index (ts/models/index.ts) so they are available through the central model exports
Update README with project overview, quick start and programmatic usage documentation

Initial release: base project skeleton and first commit.