Set up comprehensive frontend testing infrastructure

- Install Jest for unit testing with React Testing Library
- Install Playwright for end-to-end testing
- Configure Jest with proper TypeScript support and module mapping
- Create test setup files and utilities for both unit and e2e tests

Components:
* Jest configuration with coverage thresholds
* Playwright configuration with browser automation
* Unit tests for LoginForm, AuthContext, and useSocketIO hook
* E2E tests for authentication, dashboard, and agents workflows
* GitHub Actions workflow for automated testing
* Mock data and API utilities for consistent testing
* Test documentation with best practices

Testing features:
- Unit tests with 70% coverage threshold
- E2E tests with API mocking and user journey testing
- CI/CD integration for automated test runs
- Cross-browser testing support with Playwright
- Authentication system testing end-to-end

🚀 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/node_modules/cssstyle/lib/utils/propertyDescriptors.js

@@ -0,0 +1,16 @@
+"use strict";
+
+const prepareValue = require("../parsers").prepareValue;
+
+module.exports.getPropertyDescriptor = function getPropertyDescriptor(property) {
+  return {
+    set(v) {
+      this._setProperty(property, prepareValue(v));
+    },
+    get() {
+      return this.getPropertyValue(property);
+    },
+    enumerable: true,
+    configurable: true
+  };
+};