Cleaner detail pages with separated metadata and body cards

Forage item detail pages now separate metadata and rendered body content into two distinct cards. The top card shows source, requester, updated date, and domain badges, while the item body appears in its own Details card below. This applies to all forage types, including manual items, GitHub issues, and Grafana alerts, making long Markdown bodies easier to scan without pushing metadata out of view. The edit state keeps the form in the first card and hides the body card so the page stays clean while editing.