fix: use import.meta.url instead of __dirname in ESM config

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

e2e/playwright.config.ts

@@ -1,9 +1,12 @@
 import { defineConfig } from '@playwright/test';
 import dotenv from 'dotenv';
-import path from 'path';
+import { fileURLToPath } from 'url';
+import { dirname, resolve } from 'path';
 
 // Load e2e/.env.test if it exists (contains OPENAI_TEST_API_KEY)
-dotenv.config({ path: path.resolve(__dirname, '.env.test') });
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+dotenv.config({ path: resolve(__dirname, '.env.test') });
 
 /**
  * Playwright configuration for AI Weekly Synth E2E tests.