Add Nova KanbanX assistant notebook foundation

[Withphildev]

What changed

• adds durable task fields, validated lifecycle transitions, optimistic revisions, and idempotent event handling
• adds transactional migrations, integrity protection, CI, and expanded server/web tests
• integrates LoopX as a non-destructive projection with dry-run-first reconciliation and lifecycle actions
• adds project, milestone, task, checklist, progress, restart-packet, and decomposition workflows
• turns KanbanX into Nova's ADHD-friendly assistant notebook with capture, agenda, daily focus, weekly reset, snooze, reminder delivery, and recurring reminders
• preserves recurring reminder wall-clock time across DST and calendar anchors across short months
• adds the corresponding UI controls and operating documentation

Why

Nova needs a durable notebook and schedule book that agents can safely read and update without relying on chat memory or one cron job per reminder. LoopX remains authoritative for LoopX-owned identity while KanbanX provides a calm, non-destructive working projection.

Impact

Users can quickly capture thoughts and reminders, review open work, break large goals into reachable steps, and acknowledge recurring reminders without completing the underlying task. Agent callers receive revision guards, replay-safe mutations, audit history, and deterministic reminder delivery identities.

Validation

• npm test — 23 server tests and 13 web tests passed
• npm run build — server and web production builds passed
• npm run agent:smoke — passed
• isolated Nova-helper recurrence test passed
• rendered UI recurrence controls and status visually verified
• git diff --check passed