fix(browser): pass executablePath from env var in all chromium.launch() calls

- system Chromium path from PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH was not forwarded
  to the launch options, causing 'executable doesn't exist' errors in Docker

src/auth/auth.service.ts

@@ -69,7 +69,7 @@ export class AuthService {
       throw new BadRequestException(`Key file not found: ${descriptor.keyFile}`);
     }
 
-    const browser = await chromium.launch({ headless: true });
+    const browser = await chromium.launch({ headless: true, executablePath: process.env.PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH });
     try {
       const context = await browser.newContext();
       const page = await context.newPage();