fix(goal): retry ESC pause persistence before giving up the goal - #284

A transient DB failure during pauseForUserCancel would silently lose the
pause: the turnDriven mark cleared, the pause never persisted, and the next
idle event resurrected the goal against the user's explicit ESC
(shouldPreempt cannot catch ESC — it adds no user message). Retry the pause
up to twice with 50ms backoff (Effect.exit captures defects, unlike typed
retry); on exhausted retries log loudly instead of warning, so a resurrecting
goal is never invisible.

No clean fault-injection seam for the retry branch (test DB is :memory:,
pauseAndPublish is a layer closure over drizzle orDie) — happy path covered
by test/goal/turn-scope.test.ts; seam absence recorded per diagnosis policy.