Add Messagers API

Scope & Context Twenty CRM currently receives contact events only from email providers. While this works well for email communication, many businesses primarily communicate through messaging platforms. The contact event system should become communication-channel agnostic by introducing a generic messaging API that allows any messaging platform to integrate with Twenty through apps/connectors. The goal is to make messenger support extensible instead of implementing every platform inside the core application. Third-party developers should be able to build connectors for platforms such as WhatsApp, Telegram, Signal, WeChat, Facebook Messenger, Instagram Direct, Slack, Microsoft Teams, Discord, Line, Viber, SMS providers, and custom messaging systems. Current behavior CRM gets contact events only from emails. Users can connect email accounts, synchronize conversations, and view email activity inside the contact timeline. There is currently no generic infrastructure for messenge…