Introduce a DEMO_MODE env var that seeds a demo user with a fully populated
board (all widget types linked to a mock integration), blocks all mutations
server-side, shows credentials on the login page, and allows entering edit
mode without persisting changes. Fixes mock data issues (media server crash
from invalid type, calendar empty states, sparse network/media data) and
adds Docker container mocking for a complete out-of-the-box demo experience.
Thomas Camlong
35bc50c12a