Add stealth mode to browser scraper and Ronis.hr store

- Switch puppeteer to puppeteer-extra with stealth plugin to
  bypass Cloudflare bot detection
- Add Ronis.hr store config (JS-rendered, 48 products per page)
- Stealth mode patches navigator.webdriver, chrome runtime, and
  other fingerprints that Cloudflare checks

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

package.json

@@ -23,6 +23,8 @@
     "fastify": "^5.2.1",
     "p-limit": "^6.2.0",
     "puppeteer": "^24.40.0",
+    "puppeteer-extra": "^3.3.6",
+    "puppeteer-extra-plugin-stealth": "^2.11.2",
     "sql.js": "^1.11.0",
     "yaml": "^2.8.3"
   },