add initial user Management API

src/models/User.ts

@@ -0,0 +1,12 @@
+import mongoose from 'mongoose';
+
+const UserSchema = new mongoose.Schema(
+  {
+     username: {type: String, required: true, unique: true},
+     pass_hash: {type: String, required: true},
+     salt : {type: String, required: true},
+     access: [String], //rezepte, flims, abrechnung, ...
+     }, {timestamps: true}
+);
+
+export const User = mongoose.model("User", UserSchema);