User: Add experience / levels

Each drop and claim hands out 10 and 5 xp respectively.
The profile then renders the users current level based on
the formula 0.5 * sqrt(exp)

migrations/20220911230203-add-user-experience.js

@@ -0,0 +1,21 @@
+'use strict';
+
+module.exports = {
+  async up (queryInterface, Sequelize) {
+    /**
+     * Add field experience to table users
+     */
+    await queryInterface.addColumn('Users', 'experience', {
+      type: Sequelize.INTEGER,
+      allowNull: false,
+      defaultValue: 0
+    });
+  },
+
+  async down (queryInterface, Sequelize) {
+    /**
+     * Remove field experience from table users
+     */
+    await queryInterface.removeColumn('Users', 'experience');
+  }
+};