Add Wikipedia, Stack Exchange, GitLab, npm, PyPI, Docker Hub, arXiv, Lobsters, DEV.to, Medium, and Hugging Face backends to the alert plugin (16 -> 27 total). Fix PyPI backend to use RSS updates feed (web search now requires JS challenge). Fix DEV.to to use public articles API (feed_content endpoint returns empty). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>