Align backend workbench API with prototype

backend/internal/logic/projects/handlers.go

@@ -20,6 +20,7 @@ func (h *Handler) Register(router gin.IRouter) {
 	router.POST("/projects", h.createProject)
 	router.GET("/projects", h.listProjects)
 	router.GET("/projects/:id/dashboard", h.dashboard)
+	router.GET("/projects/:id/workspace", h.workspace)
 }
 
 func (h *Handler) createProject(c *gin.Context) {
@@ -76,3 +77,22 @@ func (h *Handler) dashboard(c *gin.Context) {
 	}
 	c.JSON(http.StatusOK, dashboard)
 }
+
+func (h *Handler) workspace(c *gin.Context) {
+	userID, ok := auth.CurrentUserID(c)
+	if !ok {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "missing current user"})
+		return
+	}
+	projectID, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid project id"})
+		return
+	}
+	workspace, err := h.service.Workspace(userID, uint(projectID))
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load workspace"})
+		return
+	}
+	c.JSON(http.StatusOK, workspace)
+}