[codex] Reduce AuraBuff Reminders idle CPU

[Nnoggie]

Summary

• Make AuraBuff Reminders range updates event-driven instead of polling while grouped.
• Schedule duration-threshold refreshes only when tracked auras cross a relevant threshold.

Why

AuraBuff Reminders did permanent idle work in group content even when nothing changed. The range update path and duration refresh path can both wait for game events or the next known threshold deadline.

Validation

• Manual in-game profiling with Numi Addon Profiler.
• 30s idle dungeon sample on this branch showed AuraBuff Reminders at 0.000ms total.