Reorganization of backend + new routes

backend/core/paginated.go

@@ -0,0 +1,8 @@
+package core
+
+type Paginated[T any] struct {
+	Page       int `json:"page"`
+	Limit      int `json:"limit"`
+	TotalPages int `json:"totalPages"`
+	Items      []T `json:"items"`
+}