Add board APIs, review-state support, and transport regressions

[freeskyjewel-cpu]

Summary

• add board server mutation APIs and performance stats endpoints
• add review task status support across the dashboard, CLI, and task accounting
• harden file transport inbox handling so reads and counts do not create missing inboxes
• expand CI and regression coverage for board, waiter, transport, watcher, and conflict handling

Follow-up fixes from integration review

• release task locks when work moves into review so review handoffs are not blocked
• include review counts in waiter and CLI progress output
• show a REVIEW column in the Rich terminal board to keep terminal and web views aligned

Validation

• ran targeted regression coverage for board, tasks, transport, waiter, watcher, conflicts, and spawn backends
• result: 107 tests passed