Add FEATURES.md technical feature catalog and update README docs + AI Disclosure

Co-authored-by: mgifford <116832+mgifford@users.noreply.github.com>
Agent-Logs-Url: https://github.com/mgifford/daily-dap/sessions/06a99af7-aed4-4b67-b69f-9cef4bd3ae74

Author: Copilot