feat(taskflow): add core task API, storage persistence, csv export, stats page, and test coverage

app/api/health.py

@@ -0,0 +1,18 @@
+from datetime import datetime, UTC
+
+from fastapi import APIRouter
+
+router = APIRouter()
+
+
+@router.get("/health")
+def health() -> dict:
+    """
+    Health check endpoint.
+    Returns server time in UTC ISO-8601 format.
+    """
+    return {
+        "status": "ok",
+        "server_time": datetime.now(UTC).isoformat(),
+    }
+