feat: Add Microsoft Teams integration backend

[ochmanski]

Summary

• Implements complete Microsoft Teams integration backend following existing Slack/Discord patterns
• Supports multi-tenant authentication allowing any Teams organization to connect
• Includes full data sync capabilities with Microsoft Graph API

Changes

Database Schema

• Added 5 new tables for Teams entities (integration, channels, users, events, event vectors)
• Integrated with existing member and organization tables
• Added proper indexes and relations

Workflows & Sync

• SyncTeamsWorkflow - Orchestrates syncing of teams, channels, users, and messages
• DeleteTeamsIntegrationWorkflow - Handles cleanup when integration is removed
• Step functions for fetching data via Microsoft Graph API
• Delta query support for efficient incremental syncing
• AI-powered message summarization

API Integration

• OAuth 2.0 flow with Azure AD (multi-tenant support)
• Token refresh mechanism
• API handlers for Teams operations (list channels, users, trigger sync)
• Proper error handling and status reporting

Queue Processing

• Webhook event processing for real-time updates
• Message processing and summarization queue
• Integration with existing queue infrastructure

Configuration Required

Add these environment variables:

TEAMS_CLIENT_ID=<Azure AD App Client ID>
TEAMS_CLIENT_SECRET=<Azure AD App Client Secret>

Test Plan

• OAuth flow connects successfully to Teams
• Teams/channels sync properly
• Users are fetched and stored correctly
• Messages sync with proper threading
• Token refresh works when tokens expire
• Webhook events are processed
• AI summarization generates for Teams messages

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