feat: LLMO-3330: add submitScrapeJob and lookupScrapeResults to DrsClient

[rarescheseli]

Summary

• Add submitScrapeJob method to submit scraping jobs to DRS via the Bright Data provider, supporting configurable priority (HIGH/LOW) and five dataset types (youtube_videos, youtube_comments, reddit_posts, reddit_comments, wikipedia).
• Add lookupScrapeResults method to query scraping results for a batch of URLs via the /url-lookup endpoint, returning per-URL status (available, scraping, not_found) with presigned S3 URLs for completed results.
• Add README.md

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