Closes#24333.
SlashCommandConflictHandler now treats each conflict event as the current active-conflict snapshot instead of keeping a process-lifetime history. Conflicts that remain active stay deduped, conflicts absent from the latest snapshot are dropped from dedupe state, and reintroduced conflicts notify again.
Pending notifications are also filtered against each new snapshot so a conflict that resolves and reappears inside the debounce window is emitted once instead of producing stale or duplicate feedback.
CommandService emits the conflict snapshot even when it is empty, which lets the handler observe that all conflicts have resolved.
Tests cover continuous dedupe, re-notification after resolution, partial reintroduction, the debounce snapshot path, and the pre-flush resolve/reappear edge case.
