refactor(channelserver): eliminate *sql.Rows from EventRepo.GetEventQuests

Return []EventQuest instead of a raw database cursor, removing the last
*sql.Rows leak from the repository layer. The handler now iterates a
slice, and makeEventQuest reads fields from the struct directly instead
of scanning rows twice. This makes the method fully mockable and
eliminates the risk of unclosed cursors.

server/channelserver/repo_interfaces.go

@@ -271,7 +271,7 @@ type EventRepo interface {
 	GetLoginBoosts(charID uint32) ([]loginBoost, error)
 	InsertLoginBoost(charID uint32, weekReq uint8, expiration, reset time.Time) error
 	UpdateLoginBoost(charID uint32, weekReq uint8, expiration, reset time.Time) error
-	GetEventQuests() (*sql.Rows, error)
+	GetEventQuests() ([]EventQuest, error)
 	UpdateEventQuestStartTime(tx *sql.Tx, id uint32, startTime time.Time) error
 	BeginTx() (*sql.Tx, error)
 }