Implement comprehensive frontend integration testing with Playwright

- Add Playwright E2E testing framework with cross-browser support (Chrome, Firefox)
- Create authentication helpers for CalDAV server integration
- Implement calendar interaction helpers with event creation, drag-and-drop, and view switching
- Add comprehensive drag-and-drop test suite with event cleanup
- Configure CI/CD integration with Gitea Actions for headless testing
- Support both local development and CI environments with proper dependency management
- Include video recording, screenshots, and HTML reporting for test debugging
- Handle Firefox-specific timing and interaction challenges with force clicks and timeouts

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/e2e/node_modules/playwright/lib/matchers/matcherHint.js

@@ -0,0 +1,63 @@
+"use strict";
+var __defProp = Object.defineProperty;
+var __getOwnPropDesc = Object.getOwnPropertyDescriptor;
+var __getOwnPropNames = Object.getOwnPropertyNames;
+var __hasOwnProp = Object.prototype.hasOwnProperty;
+var __export = (target, all) => {
+  for (var name in all)
+    __defProp(target, name, { get: all[name], enumerable: true });
+};
+var __copyProps = (to, from, except, desc) => {
+  if (from && typeof from === "object" || typeof from === "function") {
+    for (let key of __getOwnPropNames(from))
+      if (!__hasOwnProp.call(to, key) && key !== except)
+        __defProp(to, key, { get: () => from[key], enumerable: !(desc = __getOwnPropDesc(from, key)) || desc.enumerable });
+  }
+  return to;
+};
+var __toCommonJS = (mod) => __copyProps(__defProp({}, "__esModule", { value: true }), mod);
+var matcherHint_exports = {};
+__export(matcherHint_exports, {
+  ExpectError: () => ExpectError,
+  isJestError: () => isJestError,
+  kNoElementsFoundError: () => kNoElementsFoundError,
+  matcherHint: () => matcherHint
+});
+module.exports = __toCommonJS(matcherHint_exports);
+var import_utils = require("playwright-core/lib/utils");
+const kNoElementsFoundError = "<element(s) not found>";
+function matcherHint(state, locator, matcherName, expression, actual, matcherOptions, timeout, expectedReceivedString, preventExtraStatIndent = false) {
+  let header = state.utils.matcherHint(matcherName, expression, actual, matcherOptions).replace(/ \/\/ deep equality/, "") + " failed\n\n";
+  const extraSpace = preventExtraStatIndent ? "" : " ";
+  if (locator)
+    header += `Locator: ${extraSpace}${String(locator)}
+`;
+  if (expectedReceivedString)
+    header += `${expectedReceivedString}
+`;
+  if (timeout)
+    header += `Timeout: ${extraSpace}${timeout}ms
+`;
+  return header;
+}
+class ExpectError extends Error {
+  constructor(jestError, customMessage, stackFrames) {
+    super("");
+    this.name = jestError.name;
+    this.message = jestError.message;
+    this.matcherResult = jestError.matcherResult;
+    if (customMessage)
+      this.message = customMessage + "\n\n" + this.message;
+    this.stack = this.name + ": " + this.message + "\n" + (0, import_utils.stringifyStackFrames)(stackFrames).join("\n");
+  }
+}
+function isJestError(e) {
+  return e instanceof Error && "matcherResult" in e;
+}
+// Annotate the CommonJS export names for ESM import in node:
+0 && (module.exports = {
+  ExpectError,
+  isJestError,
+  kNoElementsFoundError,
+  matcherHint
+});