feat(server): add brand kit management and project binding

Add a brand kit domain with memory and postgres stores, a BrandKitService
for CRUD and resolution, and REST endpoints to list, upsert, and delete
brand kits. Projects can bind a brand kit whose resolved context and
reference images feed into the agent's long-term memory and design prompts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/internal/infrastructure/memory/brand_kit_store.go

@@ -0,0 +1,105 @@
+package memory
+
+import (
+	"context"
+	"sort"
+	"sync"
+
+	"img_infinite_canvas/internal/domain/brandkit"
+)
+
+type BrandKitStore struct {
+	mu   sync.RWMutex
+	kits map[string]brandkit.Kit
+}
+
+func NewBrandKitStore() *BrandKitStore {
+	return &BrandKitStore{kits: make(map[string]brandkit.Kit)}
+}
+
+func (s *BrandKitStore) List(ctx context.Context, userID string) ([]brandkit.Kit, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	items := make([]brandkit.Kit, 0)
+	for _, kit := range s.kits {
+		if kit.UserID == userID {
+			items = append(items, brandkit.Clone(kit))
+		}
+	}
+	sort.SliceStable(items, func(i, j int) bool {
+		if items[i].UpdatedAt.Equal(items[j].UpdatedAt) {
+			return items[i].ID < items[j].ID
+		}
+		return items[i].UpdatedAt.After(items[j].UpdatedAt)
+	})
+	return items, nil
+}
+
+func (s *BrandKitStore) Get(ctx context.Context, userID string, id string) (brandkit.Kit, error) {
+	if err := ctx.Err(); err != nil {
+		return brandkit.Kit{}, err
+	}
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	kit, ok := s.kits[id]
+	if !ok || kit.UserID != userID {
+		return brandkit.Kit{}, brandkit.ErrNotFound
+	}
+	return brandkit.Clone(kit), nil
+}
+
+func (s *BrandKitStore) GetDefault(ctx context.Context, userID string) (brandkit.Kit, error) {
+	if err := ctx.Err(); err != nil {
+		return brandkit.Kit{}, err
+	}
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	for _, kit := range s.kits {
+		if kit.UserID == userID && kit.IsDefault {
+			return brandkit.Clone(kit), nil
+		}
+	}
+	return brandkit.Kit{}, brandkit.ErrNotFound
+}
+
+func (s *BrandKitStore) Upsert(ctx context.Context, kit brandkit.Kit) (brandkit.Kit, error) {
+	if err := ctx.Err(); err != nil {
+		return brandkit.Kit{}, err
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if existing, ok := s.kits[kit.ID]; ok && existing.UserID != kit.UserID {
+		return brandkit.Kit{}, brandkit.ErrConflict
+	}
+	if kit.IsDefault {
+		for id, candidate := range s.kits {
+			if candidate.UserID == kit.UserID && candidate.IsDefault && id != kit.ID {
+				candidate.IsDefault = false
+				s.kits[id] = candidate
+			}
+		}
+	}
+	s.kits[kit.ID] = brandkit.Clone(kit)
+	return brandkit.Clone(kit), nil
+}
+
+func (s *BrandKitStore) Delete(ctx context.Context, userID string, id string) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	kit, ok := s.kits[id]
+	if !ok || kit.UserID != userID {
+		return brandkit.ErrNotFound
+	}
+	delete(s.kits, id)
+	return nil
+}
+
+func (s *BrandKitStore) Close() error {
+	return nil
+}

server/internal/infrastructure/memory/project_repository.go

@@ -38,13 +38,14 @@ func (r *ProjectRepository) List(ctx context.Context) ([]design.ProjectSummary,
 			continue
 		}
 		items = append(items, design.ProjectSummary{
-			ID:        project.ID,
-			UserID:    project.UserID,
-			Title:     project.Title,
-			Brief:     project.Brief,
-			Status:    project.Status,
-			Thumbnail: project.Thumbnail,
-			UpdatedAt: project.UpdatedAt,
+			ID:         project.ID,
+			UserID:     project.UserID,
+			Title:      project.Title,
+			Brief:      project.Brief,
+			Status:     project.Status,
+			Thumbnail:  project.Thumbnail,
+			BrandKitID: project.BrandKitID,
+			UpdatedAt:  project.UpdatedAt,
 		})
 	}
 	return items, nil
@@ -207,6 +208,7 @@ func repositoryUserID(ctx context.Context, userID string) string {
 
 func cloneProject(project design.Project) design.Project {
 	project.UserID = repositoryUserID(context.Background(), project.UserID)
+	project.BrandImages = append([]string(nil), project.BrandImages...)
 	project.Nodes = append([]design.Node(nil), project.Nodes...)
 	project.Connections = append([]design.Connection(nil), project.Connections...)
 	project.Messages = append([]design.Message(nil), project.Messages...)