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/playwright.config.ts

@@ -0,0 +1,91 @@
+import { defineConfig, devices } from '@playwright/test';
+
+/**
+ * @see https://playwright.dev/docs/test-configuration
+ */
+export default defineConfig({
+  testDir: './tests',
+  /* Run tests in files in parallel */
+  fullyParallel: true,
+  /* Fail the build on CI if you accidentally left test.only in the source code. */
+  forbidOnly: !!process.env.CI,
+  /* Retry on CI only */
+  retries: process.env.CI ? 2 : 0,
+  /* Opt out of parallel tests on CI. */
+  workers: process.env.CI ? 1 : undefined,
+  /* Set test timeout to 45 seconds */
+  timeout: 45000,
+  /* Reporter to use. See https://playwright.dev/docs/test-reporters */
+  reporter: [
+    ['html'],
+    ['junit', { outputFile: 'results.xml' }]
+  ],
+  /* Shared settings for all the projects below. See https://playwright.dev/docs/api/class-testoptions. */
+  use: {
+    /* Base URL to use in actions like `await page.goto('/')`. */
+    baseURL: 'http://localhost:8080',
+
+    /* Set larger viewport for better visibility of modals and forms */
+    viewport: { width: 1920, height: 1080 },
+
+    /* Collect trace when retrying the failed test. See https://playwright.dev/docs/trace-viewer */
+    trace: 'on-first-retry',
+    
+    /* Take screenshot on failure */
+    screenshot: 'only-on-failure',
+    
+    /* Record video for all tests */
+    video: 'on',
+  },
+
+  /* Configure projects for major browsers */
+  projects: [
+    {
+      name: 'chromium',
+      use: { 
+        ...devices['Desktop Chrome'],
+        // Force headless mode for CI
+        headless: !!process.env.CI,
+        // Override device viewport with larger size
+        viewport: { width: 1920, height: 1080 },
+      },
+    },
+
+    {
+      name: 'firefox',
+      use: { 
+        ...devices['Desktop Firefox'],
+        // Force headless mode for CI
+        headless: !!process.env.CI,
+        // Override device viewport with larger size
+        viewport: { width: 1920, height: 1080 },
+      },
+    },
+
+    // Skip WebKit/Safari for headless CI server
+    // Uncomment for local testing with Safari
+    // {
+    //   name: 'webkit',
+    //   use: { ...devices['Desktop Safari'] },
+    // },
+
+    /* Test against mobile viewports. */
+    // {
+    //   name: 'Mobile Chrome',
+    //   use: { ...devices['Pixel 5'] },
+    // },
+    // {
+    //   name: 'Mobile Safari',
+    //   use: { ...devices['iPhone 12'] },
+    // },
+  ],
+
+  /* Run your local dev server before starting the tests */
+  webServer: {
+    command: 'trunk serve --port 8080',
+    port: 8080,
+    cwd: '../',
+    reuseExistingServer: !process.env.CI,
+    timeout: 120000, // 2 minutes for WASM compilation
+  },
+});