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/clip.js

@@ -0,0 +1,54 @@
+"use strict";
+// deprecated
+// @see https://drafts.fxtf.org/css-masking/#clip-property
+
+const parsers = require("../parsers");
+const strings = require("../utils/strings");
+
+module.exports.parse = function parse(v) {
+  if (v === "") {
+    return v;
+  }
+  const val = parsers.parseKeyword(v, ["auto"]);
+  if (val) {
+    return val;
+  }
+  // parse legacy <shape>
+  v = strings.asciiLowercase(v);
+  const matches = v.match(/^rect\(\s*(.*)\s*\)$/);
+  if (!matches) {
+    return;
+  }
+  const parts = matches[1].split(/\s*,\s*/);
+  if (parts.length !== 4) {
+    return;
+  }
+  const valid = parts.every(function (part, index) {
+    const measurement = parsers.parseMeasurement(part.trim());
+    parts[index] = measurement;
+    return typeof measurement === "string";
+  });
+  if (!valid) {
+    return;
+  }
+  return `rect(${parts.join(", ")})`;
+};
+
+module.exports.isValid = function isValid(v) {
+  if (v === "") {
+    return true;
+  }
+  return typeof module.exports.parse(v) === "string";
+};
+
+module.exports.definition = {
+  set(v) {
+    v = parsers.prepareValue(v, this._global);
+    this._setProperty("clip", module.exports.parse(v));
+  },
+  get() {
+    return this.getPropertyValue("clip");
+  },
+  enumerable: true,
+  configurable: true
+};