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/string-length/index.d.ts

@@ -0,0 +1,22 @@
+/**
+Get the real length of a string - by correctly counting astral symbols and ignoring [ansi escape codes](https://github.com/sindresorhus/strip-ansi).
+
+`String#length` erroneously counts [astral symbols](https://web.archive.org/web/20150721114550/http://www.tlg.uci.edu/~opoudjis/unicode/unicode_astral.html) as two characters.
+
+@example
+```
+import stringLength = require('string-length');
+
+'🐴'.length;
+//=> 2
+
+stringLength('🐴');
+//=> 1
+
+stringLength('\u001B[1municorn\u001B[22m');
+//=> 7
+```
+*/
+declare function stringLength(string: string): number;
+
+export = stringLength;