Combat: auto-play timed-out turn-based sessions to a real win/loss

A combat session abandoned past its 1h TTL is now resumed from persisted
mid-state and auto-played through the shared resolver to a real win or
loss, rather than flatly marked as a retreat. The bulk-UPDATE sweep is
replaced by listExpiredCombatSessions plus a reaper that locks the user,
auto-plays the fight, runs the normal close-out, and DMs the outcome.
markCombatSessionExpired remains the terminal fallback for sessions that
can't be reconstructed. Wired into eventTicker.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/adventure_events.go

@@ -53,6 +53,9 @@ func (p *AdventurePlugin) eventTicker() {
 			// Expire stale pending events every tick
 			expireAdvPendingEvents()
 
+			// Auto-play any combat sessions past their 1h timeout.
+			p.reapExpiredCombatSessions()
+
 			advEventScheduleMu.Lock()
 			if advEventScheduleDay != dateKey {
 				advEventSchedule = make(map[string]int)