fix: remove duplicate AI Gateways collection (#2525)

fix: remove duplicate AI Gateways collection record (fixes #2515)

Remove the older 'LLM Gateway & Proxy' collection (10115) which overlaps
with the newer, better-curated 'AI Gateways' collection (10142). The two
collections covered the same topic with 3 shared repos. The kept collection
(10142) has 13 focused gateway/proxy projects vs the removed one's mix of
gateway and non-gateway repos.

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

Author: sykp241095