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/lib/fixtures.ts

@@ -0,0 +1,143 @@
+import { test as base, expect } from '@playwright/test';
+import { PhantomApiClient, apiClient } from './api-client';
+import { EventGenerator, TestProducts } from './event-generator';
+import { runPricingPipeline, waitForPriceUpdate, PipelineResult } from './pipeline-runner';
+import { testConfig } from '../playwright.config';
+
+/**
+ * Extended test fixtures for PHANTOM E2E tests
+ */
+export interface PhantomTestFixtures {
+  /** API client for interacting with PHANTOM services */
+  api: PhantomApiClient;
+
+  /** Event generator for creating test events */
+  events: EventGenerator;
+
+  /** Run the pricing pipeline and wait for updates */
+  triggerPriceUpdate: (options?: {
+    storeMode?: 'hotel' | 'airline';
+    highThreshold?: number;
+    lowThreshold?: number;
+    surgeMultiplier?: number;
+    discountMultiplier?: number;
+  }) => Promise<PipelineResult>;
+
+  /** Wait for a specific price condition */
+  waitForPrice: (
+    productId: string,
+    condition: (price: number, basePrice: number) => boolean,
+    storeMode?: 'hotel' | 'airline'
+  ) => Promise<{ price: number; basePrice: number; markup: number }>;
+
+  /** Test configuration */
+  config: typeof testConfig;
+}
+
+/**
+ * Custom test with PHANTOM fixtures
+ */
+export const test = base.extend<PhantomTestFixtures>({
+  api: async ({}, use) => {
+    await use(apiClient);
+  },
+
+  events: async ({}, use) => {
+    // Create a new event generator with a fresh session for each test
+    const generator = new EventGenerator({
+      storeMode: 'hotel',
+    });
+    await use(generator);
+  },
+
+  triggerPriceUpdate: async ({}, use) => {
+    const trigger = async (options = {}) => {
+      const result = await runPricingPipeline({
+        storeMode: 'hotel',
+        highThreshold: testConfig.pricing.highThreshold,
+        lowThreshold: testConfig.pricing.lowThreshold,
+        surgeMultiplier: testConfig.pricing.surgeMultiplier,
+        discountMultiplier: testConfig.pricing.discountMultiplier,
+        ...options,
+      });
+
+      // Wait a moment for Redis to be fully updated
+      await new Promise(resolve => setTimeout(resolve, 500));
+
+      return result;
+    };
+
+    await use(trigger);
+  },
+
+  waitForPrice: async ({ api }, use) => {
+    const waiter = async (
+      productId: string,
+      condition: (price: number, basePrice: number) => boolean,
+      storeMode: 'hotel' | 'airline' = 'hotel'
+    ) => {
+      let lastPrice = 0;
+      let lastBasePrice = 0;
+
+      const updated = await waitForPriceUpdate(async () => {
+        const priceResponse = await api.getPrice(storeMode, productId);
+        lastPrice = priceResponse.price;
+        lastBasePrice = priceResponse.base_price;
+        return condition(priceResponse.price, priceResponse.base_price);
+      });
+
+      if (!updated) {
+        throw new Error(
+          `Price condition not met within timeout. Last price: ${lastPrice}, base: ${lastBasePrice}`
+        );
+      }
+
+      return {
+        price: lastPrice,
+        basePrice: lastBasePrice,
+        markup: lastPrice / lastBasePrice,
+      };
+    };
+
+    await use(waiter);
+  },
+
+  config: async ({}, use) => {
+    await use(testConfig);
+  },
+});
+
+export { expect };
+
+/**
+ * Helper assertions for pricing tests
+ */
+export const PricingAssertions = {
+  /**
+   * Assert that a price has surge markup applied
+   */
+  isSurged: (price: number, basePrice: number, expectedMultiplier: number, tolerance = 0.01) => {
+    const actualMarkup = price / basePrice;
+    const minExpected = expectedMultiplier * (1 - tolerance);
+    const maxExpected = expectedMultiplier * (1 + tolerance);
+    return actualMarkup >= minExpected && actualMarkup <= maxExpected;
+  },
+
+  /**
+   * Assert that a price has discount applied
+   */
+  isDiscounted: (price: number, basePrice: number, expectedMultiplier: number, tolerance = 0.01) => {
+    const actualMarkup = price / basePrice;
+    const minExpected = expectedMultiplier * (1 - tolerance);
+    const maxExpected = expectedMultiplier * (1 + tolerance);
+    return actualMarkup >= minExpected && actualMarkup <= maxExpected;
+  },
+
+  /**
+   * Assert that a price is at base (no surge/discount)
+   */
+  isBase: (price: number, basePrice: number, tolerance = 0.01) => {
+    const actualMarkup = price / basePrice;
+    return actualMarkup >= (1 - tolerance) && actualMarkup <= (1 + tolerance);
+  },
+};