IAV-1416/bugfix(integrations): add unlink-only integration delete and fix Teams occupancy checks
- AgentIntegrationController: support DELETE ...?unlinkOnly=true to remove orchestration link while preserving N8N credentials and UserIntegration row; add AgentIntegrationService.unlinkAgentIntegration implementation.
- Teams binding occupancy: exclude the current agentUid (not just agentIntegrationUid) to avoid false conflicts when switching integrations within the same agent.
- Replicate integration: minor reordering/cleanup while keeping behaviour.