Add IAM scaffold modules

iam/internal/service/iam.go

@@ -0,0 +1,18 @@
+package service
+
+import (
+	"todo-vibe-coding/iam/internal/auth/jwt"
+	"todo-vibe-coding/iam/internal/repo"
+)
+
+type IAM struct {
+	tokens *jwt.Manager
+	users  repo.UserStore
+}
+
+func NewIAM() *IAM {
+	return &IAM{
+		tokens: jwt.NewManager("dev-secret"),
+		users:  repo.NewInMemoryUserStore(),
+	}
+}