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/v8-to-istanbul/lib/range.js

@@ -0,0 +1,35 @@
+/**
+ * ...something resembling a binary search, to find the lowest line within the range.
+ * And then you could break as soon as the line is longer than the range...
+ */
+module.exports.sliceRange = (lines, startCol, endCol, inclusive = false) => {
+  let start = 0
+  let end = lines.length
+
+  if (inclusive) {
+    // I consider this a temporary solution until I find an alternaive way to fix the "off by one issue"
+    --startCol
+  }
+
+  while (start < end) {
+    let mid = (start + end) >> 1
+    if (startCol >= lines[mid].endCol) {
+      start = mid + 1
+    } else if (endCol < lines[mid].startCol) {
+      end = mid - 1
+    } else {
+      end = mid
+      while (mid >= 0 && startCol < lines[mid].endCol && endCol >= lines[mid].startCol) {
+        --mid
+      }
+      start = mid + 1
+      break
+    }
+  }
+
+  while (end < lines.length && startCol < lines[end].endCol && endCol >= lines[end].startCol) {
+    ++end
+  }
+
+  return lines.slice(start, end)
+}