Add tasks, content, and assets

Tasks are for execution ownership, priority, blockers, and due dates.

Content items are for planned campaign messages, channels, status, and schedule.

Assets are for campaign creative, files, links, and review-ready deliverables.

For a first test, add one of each: one task, one content item, and one asset.

That is enough to see dashboard, calendar, asset library, and readiness signals start to work.