Add comprehensive testing framework for both single site and multisite WordPress environments

cypress.config.js

@@ -0,0 +1,10 @@
+const { defineConfig } = require('cypress');
+
+module.exports = defineConfig({
+  e2e: {
+    baseUrl: 'http://localhost:8888',
+    setupNodeEvents(on, config) {
+      // implement node event listeners here
+    },
+  },
+});