Add WebSearchTool that queries the self-hosted SearXNG metasearch engine
for current information, documentation, and facts beyond training data.
- Add SEARXNG_URL and SEARXNG_TIMEOUT config settings
- Create WebSearchTool with query, num_results, categories params
- Register web_search tool with explore agent
- Add 10 tests for search functionality
Usage: Agents can now use web_search(query="...") to find current info.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
