T09: KI-Copilot API + Hybrid Workflow Engine + LLM client + event-triggered workflows

- KI-Copilot: NL query → proposed actions, execute with RBAC, history, audit logging
- LLM client: mock mode (no API key) + OpenAI-compatible mode (AI_MODEL/AI_API_KEY)
- Action mapper: NL intent → API calls (create/update/delete/search company/contact)
- Workflow engine: step types (action/approval/notification/condition), JSONB steps
- Workflow lifecycle: pending → in_progress → completed/rejected/cancelled
- Event-triggered workflows: event bus → auto-start instances
- Code-engine workflows: onboarding on user.created event
- Approval timeout: auto-reject after configured hours
- 5 new tenant-scoped tables with RLS: ai_conversations, ai_messages, workflows, workflow_instances, workflow_step_history
- Migration 0004: all tables + RLS policies + tenant_id + indexes
- 238 tests pass (30 AC + 105 coverage + 103 existing), 84.12% T09 module coverage
- MissingGreenlet fix: safe accessor helpers for async ORM attribute access

app/schemas/__init__.py

@@ -1,3 +1,13 @@
 """Pydantic schemas package."""
 
 from app.schemas.plugin import PluginInfo, PluginListResponse, PluginActionResponse, PluginUninstallResponse
+from app.schemas.ai_copilot import (
+    CopilotQueryRequest, CopilotAction, CopilotQueryResponse,
+    CopilotExecuteRequest, CopilotExecuteResponse,
+    CopilotHistoryResponse, CopilotMessageResponse,
+)
+from app.schemas.workflow import (
+    WorkflowCreate, WorkflowUpdate, WorkflowResponse, WorkflowListResponse,
+    InstanceCreate, InstanceResponse, InstanceDetailResponse, InstanceListResponse,
+    AdvanceRequest, StepHistoryResponse, WorkflowStep,
+)