Send planning items to Kanban (Boards module)

If the Boards module is enabled on your org, you can spawn kanban cards from planning tasks, milestones, or phases.

Per-item:
• Each task row has a small **→ board** pill. Click to open a picker, choose a board + list, and a card is created in that column.

Bulk:
• On the Tasks tab, click **Send N to a board** (visible when at least one task is in the current filter). Creates one card per item.

What the card looks like:
• Title = the task / milestone / phase name
• Description = the original notes + a link back to the project (`[<project name>](/planning?open=<id>)`) + the task's date range
• `linkedRef` = the planning task id, so future bidirectional sync (v5) can detect the relationship

Use cases:
• A construction project's milestones become punch-list cards on a delivery board
• A product launch's tasks fan out to engineering and marketing kanban boards
• Phase kickoffs become "ready to start" cards in your weekly planning board

Note:
• v4 is **one-directional** — completing the kanban card does NOT mark the planning task done. v5 will add the reverse link with an optional auto-status mirror.
• If you re-send the same item, you'll get a duplicate card. We deliberately don't dedupe in v4 — you may want a fresh card on a new board for a different cycle.