refactor(channelserver): eliminate *sqlx.Rows/*sql.Rows from repository interfaces

Move scan loops from handlers into repository methods so that interfaces
return typed slices instead of leaking database cursors. This fixes
resource leaks (7 of 12 call sites never closed rows) and makes all
12 methods mockable for unit tests.

Affected repos: CafeRepo, ShopRepo, EventRepo, RengokuRepo, DivaRepo,
ScenarioRepo, MiscRepo, MercenaryRepo. New structs: DivaEvent,
MercenaryLoan, GuildHuntCatUsage. EventRepo.GetEventQuests left as-is
(requires broader Server refactor).

server/channelserver/handlers_diva.go

@@ -78,16 +78,13 @@ func handleMsgMhfGetUdSchedule(s *Session, p mhfpacket.MHFPacket) {
 
 	const divaIDSentinel = uint32(0xCAFEBEEF)
 	id, start := divaIDSentinel, uint32(0)
-	rows, err := s.server.divaRepo.GetEvents()
+	events, err := s.server.divaRepo.GetEvents()
 	if err != nil {
 		s.logger.Error("Failed to query diva schedule", zap.Error(err))
-	} else {
-		defer func() { _ = rows.Close() }()
-		for rows.Next() {
-			if err := rows.Scan(&id, &start); err != nil {
-				s.logger.Error("Failed to scan diva schedule row", zap.Error(err))
-			}
-		}
+	} else if len(events) > 0 {
+		last := events[len(events)-1]
+		id = last.ID
+		start = last.StartTime
 	}
 
 	var timestamps []uint32