feat: publish standalone worker

Separate worker packaging and service lifecycle from the control plane.

app/models/concerns/timestamped.go

@@ -0,0 +1,11 @@
+package concerns
+
+import (
+	"time"
+)
+
+// Timestamped provides functionality.
+type Timestamped struct {
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}