Update LICENSE file and add AGPL header to all source files.
AGPLv3 ensures that if someone runs Kafka as a network service and
modifies it, they must release their source code under the same license.
- google.go: use inline (?s) flag instead of regexp.DotAll second arg
- youtube.go: remove Metadata field (not in MainResult contract)
- config_test.go: fix expected engine count from 9 to 11 (google+youtube)
Uses the official YouTube Data API v3. Requires YOUTUBE_API_KEY
environment variable (free from Google Cloud Console).
Returns video results with title, description, channel, publish
date, and thumbnail URL. Falls back gracefully if no API key.
