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/handler/project_events_handler.go

@@ -0,0 +1,58 @@
+// Code scaffolded by goctl. Safe to edit.
+// goctl 1.10.1
+
+package handler
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"img_infinite_canvas/internal/logic"
+	"img_infinite_canvas/internal/svc"
+	"img_infinite_canvas/internal/types"
+)
+
+func projectEventsHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req types.ProjectIdRequest
+		if err := httpx.Parse(r, &req); err != nil {
+			httpx.ErrorCtx(r.Context(), w, err)
+			return
+		}
+		flusher, ok := w.(http.Flusher)
+		if !ok {
+			httpx.ErrorCtx(r.Context(), w, fmt.Errorf("streaming is not supported"))
+			return
+		}
+
+		header := w.Header()
+		header.Set("Content-Type", "text/event-stream")
+		header.Set("Cache-Control", "no-cache")
+		header.Set("Connection", "keep-alive")
+		header.Set("X-Accel-Buffering", "no")
+
+		l := logic.NewProjectEventsLogic(r.Context(), svcCtx)
+		threadID := r.URL.Query().Get("threadId")
+		if threadID == "" {
+			threadID = r.URL.Query().Get("thread_id")
+		}
+		err := l.Stream(&req, threadID, func(event string, payload any) error {
+			data, err := json.Marshal(payload)
+			if err != nil {
+				return err
+			}
+			if _, err := fmt.Fprintf(w, "event: %s\ndata: %s\n\n", event, data); err != nil {
+				return err
+			}
+			flusher.Flush()
+			return nil
+		})
+		if err != nil && r.Context().Err() == nil {
+			data, _ := json.Marshal(map[string]string{"error": err.Error()})
+			_, _ = fmt.Fprintf(w, "event: stream_error\ndata: %s\n\n", data)
+			flusher.Flush()
+		}
+	}
+}