Initial commit: img-infinite-canvas AI design workbench MVP

Moteva-style AI design workbench replica. Home prompt creates a project;
the project page provides an infinite canvas with node drag, zoom/pan,
a design chat panel, history replay, image asset upload, and project
save/regenerate.

- Backend: go-zero, DDD layering, sqlc/pgx, optional PostgreSQL; memory
  or Redis cache; asynq job queue; MinIO/S3/R2/OSS object storage;
  sky-valley/pi agent runtime adapter.
- Frontend: Next.js App Router + Vite artifact build, TypeScript, i18n,
  shadcn/ui components, auth (OTP/Turnstile/Google/WeChat).
- Deploy: Docker Compose and k3s manifests.

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

server/internal/modules/realtime/event.go

@@ -0,0 +1,28 @@
+package realtime
+
+import (
+	"context"
+	"encoding/json"
+	"time"
+)
+
+type Event struct {
+	ID        string          `json:"id"`
+	UserID    string          `json:"userId"`
+	ProjectID string          `json:"projectId"`
+	ThreadID  string          `json:"threadId,omitempty"`
+	Type      string          `json:"type"`
+	Payload   json.RawMessage `json:"payload,omitempty"`
+	CreatedAt time.Time       `json:"createdAt"`
+}
+
+type Bus interface {
+	Publish(ctx context.Context, event Event) error
+	Subscribe(ctx context.Context, projectID string) (Subscription, error)
+	Close() error
+}
+
+type Subscription interface {
+	C() <-chan Event
+	Close() error
+}