IAV-1332/bugfix(teams-channels): add integration Teams binding model and agent tenant/notification routing
- Add AgentIntegrationTeamsBinding (agent_integration_teams_bindings) with team/channel, optional notification team/channel, m365 tenant id, and agent_integration_uid.
- LegalAgent: persist microsoft_teams_m365_tenant_id for Entra tid forwarding.
- PublicMarketAgent: optional notification team/channel ids + m365 tenant id with effective* helpers falling back to main integration ids.