[codex] Remove missed alarm catch-up scheduling

[jjoonleo]

Summary

• Remove the remaining missed-alarm catch-up path from alarm reconciliation.
• Keep reconciliation limited to alarms whose computed alarm time is still in the future.
• Update regression tests so just-missed alarms are skipped and already armed just-missed alarms are cleaned up instead of rearmed.

Root cause

A previous commit removed the near-term schedule catch-up path, but the older recently-missed alarm catch-up path still adjusted past alarm times to now + 5 seconds. On iOS, app resume reconciliation could therefore schedule another native alarm shortly after the original 5-minute-before alarm had already fired.

Validation

• rg -n "recentlyMissed|missedAlarmCatchUp|DeliveryDelay|GracePeriod|adjustedAlarmTime|isRecentlyMissed|isUpcomingScheduleCatchUp" lib test || true returned no matches.
• flutter test test/domain/use-cases/reconcile_alarms_use_case_test.dart
• flutter analyze