Implement FastAPI Temporal MVP pipeline

app/domain/models/workflow_step.py

@@ -0,0 +1,23 @@
+"""Domain workflow step model."""
+
+from dataclasses import dataclass
+from datetime import datetime
+from typing import Any
+
+from app.domain.enums import StepStatus, WorkflowStepName
+
+
+@dataclass(slots=True)
+class WorkflowStep:
+    """Business representation of a workflow step attempt."""
+
+    id: int
+    workflow_run_id: int
+    step_name: WorkflowStepName
+    step_status: StepStatus
+    input_json: dict[str, Any] | None
+    output_json: dict[str, Any] | None
+    error_message: str | None
+    started_at: datetime
+    ended_at: datetime | None
+