refactor(festa): extract festa logic into FestaService

The festa handler contained event lifecycle management (cleanup expired
events, create new ones) and the repo enforced a business rule (skip
zero-value soul submissions). Move these into a new FestaService to
keep repos as pure data access and consolidate business logic.

server/channelserver/svc_festa.go

@@ -0,0 +1,61 @@
+package channelserver
+
+import (
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// FestaService encapsulates festa business logic, sitting between handlers and repos.
+type FestaService struct {
+	festaRepo FestaRepo
+	logger    *zap.Logger
+}
+
+// NewFestaService creates a new FestaService.
+func NewFestaService(fr FestaRepo, log *zap.Logger) *FestaService {
+	return &FestaService{
+		festaRepo: fr,
+		logger:    log,
+	}
+}
+
+// EnsureActiveEvent checks whether the current festa event is still active.
+// If it has expired or none exists, all festa state is cleaned up and a new
+// event is created starting at the next midnight. Returns the (possibly new)
+// start time.
+func (svc *FestaService) EnsureActiveEvent(currentStart uint32, now time.Time, nextMidnight time.Time) (uint32, error) {
+	if currentStart != 0 && now.Unix() <= int64(currentStart)+festaEventLifespan {
+		return currentStart, nil
+	}
+
+	if err := svc.festaRepo.CleanupAll(); err != nil {
+		svc.logger.Error("Failed to cleanup festa", zap.Error(err))
+		return 0, err
+	}
+
+	newStart := uint32(nextMidnight.Unix())
+	if err := svc.festaRepo.InsertEvent(newStart); err != nil {
+		svc.logger.Error("Failed to insert festa event", zap.Error(err))
+		return 0, err
+	}
+
+	return newStart, nil
+}
+
+// SubmitSouls filters out zero-value soul entries and records the remaining
+// submissions for the character. Returns nil if all entries are zero.
+func (svc *FestaService) SubmitSouls(charID, guildID uint32, souls []uint16) error {
+	var filtered []uint16
+	hasNonZero := false
+	for _, s := range souls {
+		filtered = append(filtered, s)
+		if s != 0 {
+			hasNonZero = true
+		}
+	}
+	if !hasNonZero {
+		return nil
+	}
+	return svc.festaRepo.SubmitSouls(charID, guildID, souls)
+}