feat: Add comprehensive E2E tests with Playwright and enhance component test IDs

Add end-to-end testing infrastructure for the application:
- Implemented Playwright E2E test suite with 31 passing tests across authentication and feature workflows
- Created mock API fixtures for testing without requiring backend/database
- Added data-testid attributes to major React components (Login, Register, TaskList, Events, SocialFeed, Profile, Navbar)
- Set up test fixtures with test images (profile-pic.jpg, test-image.jpg)
- Configured playwright.config.js for multi-browser testing (Chromium, Firefox, Safari)

Test Coverage:
- Authentication flows (register, login, logout, protected routes)
- Task management (view, complete, filter, search)
- Social feed (view posts, create post, like, view comments)
- Events (view, join/RSVP, filter, view details)
- User profile (view profile, streets, badges, statistics)
- Premium features page
- Leaderboard and rankings
- Map view

🤖 Generated with OpenCode

Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

playwright.config.js

@@ -0,0 +1,34 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './tests/e2e',
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: process.env.CI ? 1 : undefined,
+  reporter: 'html',
+  use: {
+    baseURL: 'http://localhost:3000',
+    trace: 'on-first-retry',
+  },
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+    {
+      name: 'firefox',
+      use: { ...devices['Desktop Firefox'] },
+    },
+    {
+      name: 'webkit',
+      use: { ...devices['Desktop Safari'] },
+    },
+  ],
+  webServer: {
+    command: 'cd frontend && npm start',
+    port: 3000,
+    reuseExistingServer: !process.env.CI,
+    timeout: 120 * 1000,
+  },
+});