feat(kol): cache marketplace and generation reads with singleflight

Add cache-aside + singleflight to KOL marketplace list/detail, my-subscription
prompts, and generation schema lookups. Invalidate the shared public-facing
caches when subscriptions are added/revoked (ops) or KOL profile is updated.

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

server/internal/tenant/app/kol_profile_service.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/geo-platform/tenant-api/internal/shared/auth"
+	sharedcache "github.com/geo-platform/tenant-api/internal/shared/cache"
 	"github.com/geo-platform/tenant-api/internal/shared/objectstorage"
 	"github.com/geo-platform/tenant-api/internal/shared/response"
 	"github.com/geo-platform/tenant-api/internal/tenant/repository"
@@ -15,6 +16,7 @@ var ErrNotActiveKol = response.ErrForbidden(40341, "kol_not_active", "user is no
 type KolProfileService struct {
 	repo          repository.KolProfileRepository
 	objectStorage objectstorage.Client
+	cache         sharedcache.Cache
 }
 
 type UpdateKolProfileServiceInput struct {
@@ -45,6 +47,11 @@ func (s *KolProfileService) WithObjectStorage(client objectstorage.Client) *KolP
 	return s
 }
 
+func (s *KolProfileService) WithCache(c sharedcache.Cache) *KolProfileService {
+	s.cache = c
+	return s
+}
+
 func (s *KolProfileService) RequireActiveKol(ctx context.Context, actor auth.Actor) (*repository.KolProfile, error) {
 	profile, err := s.repo.GetByUser(ctx, actor.TenantID, actor.UserID)
 	if err != nil {
@@ -91,6 +98,7 @@ func (s *KolProfileService) UpdateProfile(ctx context.Context, actor auth.Actor,
 	if updated == nil {
 		return nil, ErrNotActiveKol
 	}
+	InvalidateKolPublicCaches(ctx, s.cache)
 	return updated, nil
 }