Version 2.0.0: Animation fixes, timing improvements, and E2E test suite

Animation fixes:
- Fix held card positioning bug (was appearing at bottom of page)
- Fix discard pile blank/white flash on turn transitions
- Fix blank card at round end by skipping animations during round_over/game_over
- Set card content before triggering flip animation to prevent flash
- Center suit symbol on 10 cards

Timing improvements:
- Reduce post-discard delay from 700ms to 500ms
- Reduce post-swap delay from 1800ms to 1000ms
- Speed up swap flip animation from 1150ms to 550ms
- Reduce CPU initial thinking delay from 150-250ms to 80-150ms
- Pause now happens after swap completes (showing result) instead of before

E2E test suite:
- Add Playwright-based test bot that plays full games
- State parser extracts game state from DOM for validation
- AI brain ports decision logic for automated play
- Freeze detector monitors for UI hangs
- Visual validator checks CSS states
- Full game, stress, and visual test specs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/e2e/playwright.config.ts

@@ -0,0 +1,36 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './specs',
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: process.env.CI ? 1 : undefined,
+  reporter: [
+    ['html', { outputFolder: 'playwright-report' }],
+    ['list'],
+  ],
+  use: {
+    baseURL: process.env.TEST_URL || 'http://localhost:8000',
+    trace: 'on-first-retry',
+    screenshot: 'only-on-failure',
+    video: 'retain-on-failure',
+  },
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+    {
+      name: 'mobile',
+      use: { ...devices['iPhone 13'] },
+    },
+    {
+      name: 'tablet',
+      use: { ...devices['iPad Pro 11'] },
+    },
+  ],
+  // Note: The server must be running before tests
+  // Start it with: cd ../.. && python server/main.py
+  // webServer config removed because it requires PostgreSQL which may not be available
+});