Add dynamic pricing E2E test suite with Playwright

Implement comprehensive E2E tests to validate the surge pricing pipeline:
- Test SimpleSurgePricer with configurable thresholds (high=3, surge=1.5x)
- Verify discount pricing when demand is below low_threshold
- Test multi-product differential pricing based on demand signals
- Validate price propagation from pipeline through Redis to API

Test infrastructure:
- Playwright configuration with custom fixtures
- Python pipeline worker for direct test execution (bypasses Airflow)
- API client for event ingestion and price verification
- Event generator for creating realistic interaction sequences
- docker-compose.e2e.yml with minimal services for testing

e2e/playwright.config.ts

@@ -0,0 +1,84 @@
+import { defineConfig, devices } from '@playwright/test';
+
+/**
+ * Playwright configuration for PHANTOM Dynamic Pricing E2E Tests
+ *
+ * Tests validate the entire pricing pipeline:
+ * Frontend Events → Kafka → Pipeline Processing → Redis → Pricing API
+ */
+export default defineConfig({
+  testDir: './tests',
+  fullyParallel: false, // Run tests sequentially to avoid race conditions in shared state
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: 1, // Single worker for E2E tests to ensure isolation
+  reporter: [
+    ['html', { outputFolder: 'playwright-report' }],
+    ['list']
+  ],
+
+  // Global timeout for each test
+  timeout: 120_000, // 2 minutes per test (includes pipeline processing time)
+
+  // Expect timeout for assertions
+  expect: {
+    timeout: 30_000, // 30 seconds for price updates to propagate
+  },
+
+  use: {
+    // Base URL for the backend API
+    baseURL: process.env.BACKEND_URL || 'http://localhost:5000',
+
+    // Collect trace on first retry
+    trace: 'on-first-retry',
+
+    // Screenshot on failure
+    screenshot: 'only-on-failure',
+  },
+
+  // Global setup and teardown
+  globalSetup: require.resolve('./global-setup'),
+  globalTeardown: require.resolve('./global-teardown'),
+
+  projects: [
+    {
+      name: 'dynamic-pricing',
+      testMatch: /.*\.spec\.ts/,
+    },
+  ],
+
+  // Environment configuration
+  // These can be overridden via environment variables
+});
+
+// Export test configuration constants
+export const testConfig = {
+  // API endpoints
+  backendUrl: process.env.BACKEND_URL || 'http://localhost:5000',
+  providerUrl: process.env.PROVIDER_URL || 'http://localhost:5001',
+
+  // Redis configuration
+  redisHost: process.env.REDIS_HOST || 'localhost',
+  redisPort: parseInt(process.env.REDIS_PORT || '6378'),
+
+  // Kafka configuration
+  kafkaHost: process.env.KAFKA_HOST || 'localhost',
+  kafkaPort: parseInt(process.env.KAFKA_PORT || '9092'),
+
+  // Pricing thresholds for tests (aggressive settings for fast feedback)
+  pricing: {
+    highThreshold: 3,     // Trigger surge after 3 interactions
+    lowThreshold: 1,      // Trigger discount at 1 or fewer interactions
+    surgeMultiplier: 1.5, // 50% price increase on surge
+    discountMultiplier: 0.9, // 10% discount on low demand
+    windowSize: 10_000,   // 10 second window for demand calculation
+  },
+
+  // Timing configuration
+  timing: {
+    eventDelay: 100,           // Delay between events (ms)
+    pipelineWait: 5_000,       // Wait for pipeline processing (ms)
+    priceCheckInterval: 1_000, // Interval between price checks (ms)
+    maxPriceWait: 30_000,      // Max wait for price update (ms)
+  },
+};