feat(campaigns): derive chatwoot scheduling

internal/repository/campaign_repo.go

@@ -6,6 +6,7 @@ import (
 	"gorm.io/gorm"
 
 	"github.com/gochat/gochat/internal/campaign"
+	"github.com/gochat/gochat/internal/model"
 )
 
 // CampaignRepo implements GORM repository for Campaign.
@@ -46,6 +47,26 @@ func (r *CampaignRepo) FindByIDAndAccount(ctx context.Context, id, accountID uin
 	return r.FindByDisplayIDAndAccountOrID(ctx, id, accountID)
 }
 
+// FindInboxByIDAndAccount retrieves the campaign inbox scoped to the same account.
+func (r *CampaignRepo) FindInboxByIDAndAccount(ctx context.Context, inboxID, accountID uint) (*model.Inbox, error) {
+	var inbox model.Inbox
+	if err := r.db.WithContext(ctx).Where("id = ? AND account_id = ?", inboxID, accountID).First(&inbox).Error; err != nil {
+		return nil, err
+	}
+	return &inbox, nil
+}
+
+// AccountHasUser returns whether the user belongs to the account.
+func (r *CampaignRepo) AccountHasUser(ctx context.Context, accountID, userID uint) (bool, error) {
+	var count int64
+	if err := r.db.WithContext(ctx).Model(&model.AccountUser{}).
+		Where("account_id = ? AND user_id = ?", accountID, userID).
+		Count(&count).Error; err != nil {
+		return false, err
+	}
+	return count > 0, nil
+}
+
 // FindByDisplayIDAndAccountOrID retrieves a campaign by Chatwoot display_id, falling back to primary key for legacy callers/tests.
 func (r *CampaignRepo) FindByDisplayIDAndAccountOrID(ctx context.Context, routeID, accountID uint) (*campaign.Campaign, error) {
 	var c campaign.Campaign