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/@sinonjs/commons/lib/function-name.js

@@ -0,0 +1,28 @@
+"use strict";
+
+/**
+ * Returns a display name for a function
+ * @param  {Function} func
+ * @returns {string}
+ */
+module.exports = function functionName(func) {
+    if (!func) {
+        return "";
+    }
+
+    try {
+        return (
+            func.displayName ||
+            func.name ||
+            // Use function decomposition as a last resort to get function
+            // name. Does not rely on function decomposition to work - if it
+            // doesn't debugging will be slightly less informative
+            // (i.e. toString will say 'spy' rather than 'myFunc').
+            (String(func).match(/function ([^\s(]+)/) || [])[1]
+        );
+    } catch (e) {
+        // Stringify may fail and we might get an exception, as a last-last
+        // resort fall back to empty string.
+        return "";
+    }
+};