queen board: why bees are idle, lanes by repository or kind, and a task drawer #1554

Context

Slice 5 of the epic gHashTag/t27#7718, the dashboard. The board follows the card gHashTag/t27 specs/queen/dashboard.t27 (gHashTag/t27#7827), run as wasm. The drawer reads GET /queen/public-task (gHashTag/BrowserOS#552).

Scenarios

• Why lanes are idle. The board says why the free lanes are idle, as idle_verdict judges it from the Queen's last round in /queen/status. Examples: "48 lanes free · 31 ready issues wait their turn", or "issues wait for files another bee holds".
• Lanes. The board splits into lanes by repository or by kind (lanes=repo|kind in the address). Past LANES_MAX, the remaining lanes fold into one.
• The drawer. A task opens in a drawer (open=<key> in the address) with its history, lease, attempts and effects. A card's own click still opens its issue or its conversation. A server without the route is named as such.

Acceptance criteria

• public/t27/queen/dashboard.wasm is byte-identical to the supervisor's (sha256 2b310da3...).
• The trinity type ratchet and the language contract pass.