Didi crawl — three targets (links, streams, team members), the relevance brief, and staged team ingest

Implements the spec's §v1.2 crawl contract: one organization.crawl capability in prompt-runner riding Anthropic server-side web_search, candidates rendered through search-and-add's crawl mode (links/streams) and a staged people section on the workbench (team), all driven by a per-workspace operator-editable relevance brief.