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/properties/borderTop.js

@@ -0,0 +1,40 @@
+"use strict";
+
+const parsers = require("../parsers");
+const borderTopWidth = require("./borderTopWidth");
+const borderTopStyle = require("./borderTopStyle");
+const borderTopColor = require("./borderTopColor");
+
+const shorthandFor = new Map([
+  ["border-top-width", borderTopWidth],
+  ["border-top-style", borderTopStyle],
+  ["border-top-color", borderTopColor]
+]);
+
+module.exports.definition = {
+  set(v) {
+    v = parsers.prepareValue(v, this._global);
+    if (parsers.hasVarFunc(v)) {
+      for (const [key] of shorthandFor) {
+        this._setProperty(key, "");
+      }
+      this._setProperty("border", "");
+      this._setProperty("border-top", v);
+    } else {
+      this._shorthandSetter("border-top", v, shorthandFor);
+    }
+  },
+  get() {
+    let val = this.getPropertyValue("border-top");
+    if (parsers.hasVarFunc(val)) {
+      return val;
+    }
+    val = this._shorthandGetter("border-top", shorthandFor);
+    if (parsers.hasVarFunc(val)) {
+      return "";
+    }
+    return val;
+  },
+  enumerable: true,
+  configurable: true
+};