fix: move implementation to "internal" package

internal/handler/middleware/generate_recurring_transactions.go

@@ -0,0 +1,22 @@
+package middleware
+
+import (
+	"net/http"
+	"spend-sparrow/internal/service"
+)
+
+func GenerateRecurringTransactions(transactionRecurring service.TransactionRecurring) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			user := GetUser(r)
+			if user == nil || r.Method != http.MethodGet {
+				next.ServeHTTP(w, r)
+				return
+			}
+
+			_ = transactionRecurring.GenerateTransactions(user)
+
+			next.ServeHTTP(w, r)
+		})
+	}
+}