Facebook Ad Library Scraper

I want to use the Facebook Ad Library Scraper service on Fast Marketplace.

## Setup (skip if you already have Fast Marketplace set up)
1. Open the marketplace skill: https://marketplace.fast.xyz/skill.md
2. Fund a Fast wallet on mainnet.
3. Provide either an Ad Library search URL or a list of Facebook page URLs.
4. Keep the returned job token and poll the marketplace job route for completion.

## Available Endpoints

### Search Ads ($0.0001 USDC)
curl -X POST "https://api.marketplace.fast.xyz/api/apify-facebook-ads-library/search-ads" \
  -H "Content-Type: application/json" \
  -d '{
  "searchPageUrl": "https://www.facebook.com/ads/library/?active_status=all&ad_type=all&country=US&q=fast",
  "scrapeAdDetails": true
}'

Use an Ad Library search URL for keyword monitoring, or page URLs when you already know the advertisers you want to track.

For paid endpoints: the first call returns 402. Authorize payment with your Fast wallet and retry with the payment signature header.