Closes the audit finding: a crash between 'sink accepted it' and 'we
recorded that' caused duplicate sends on the next tick with no trace.
BeginDeliveryAttempt now runs before Send, CompleteDeliveryAttempt
after — a stale 'pending' row found at startup reconciles to 'unknown'
(never silently resent, never silently dropped, same rule as the Hexis
execution engine's timeout handling). Wired into DispatchNudge,
DispatchReminder, and RepeatUnacked; ReconcileStaleDeliveryAttempts
runs once at mavend startup before the tick loop resumes.
9 new dispatcher tests cover begin-before-send ordering, failed-send
completion, the reminder path, and begin-failure not blocking send.
Vikunja #270.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018ghELqYhZNLub2TXGMazqA
kami
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