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/@testing-library/user-event/dist/esm/document/copySelection.js

@@ -0,0 +1,27 @@
+import { createDataTransfer } from '../utils/dataTransfer/DataTransfer.js';
+import '../utils/dataTransfer/Clipboard.js';
+import { getWindow } from '../utils/misc/getWindow.js';
+import { hasOwnSelection } from '../utils/focus/selection.js';
+import { getUISelection, getUIValue } from './UI.js';
+
+function copySelection(target) {
+    const data = hasOwnSelection(target) ? {
+        'text/plain': readSelectedValueFromInput(target)
+    } : {
+        'text/plain': String(target.ownerDocument.getSelection())
+    };
+    const dt = createDataTransfer(getWindow(target));
+    for(const type in data){
+        if (data[type]) {
+            dt.setData(type, data[type]);
+        }
+    }
+    return dt;
+}
+function readSelectedValueFromInput(target) {
+    const sel = getUISelection(target);
+    const val = getUIValue(target);
+    return val.substring(sel.startOffset, sel.endOffset);
+}
+
+export { copySelection };