refactor(backend): isolate workspace aggregation

backend/internal/logic/projects/handlers.go

@@ -140,14 +140,13 @@ func (h *Handler) workspace(c *gin.Context) {
 		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"})
+	projectIdentity, ok := httpx.IdentityParam(c, "id")
+	if !ok {
 		return
 	}
-	workspace, err := h.service.Workspace(userID, uint(projectID))
+	workspace, err := h.service.Workspace(userID, projectIdentity)
 	if err != nil {
-		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load workspace"})
+		writeProjectError(c, err)
 		return
 	}
 	c.JSON(http.StatusOK, workspace)