调整图片画布路由和画布数据模型

将图片画布入口改为 /editor/canvas

新增 editor_canvas 表并关联 editor_project 默认画布

更新 project API 响应中的 canvas 快照兼容层

统一图片画布侧栏列表项和图标按钮组件

同步前端测试、SpacetimeDB bindings、技术文档和 TRACKING 记录

src/services/image-editor/editorProjectClient.ts

@@ -68,12 +68,23 @@ export type EditorImageGenerationResult = {
 export type EditorProjectSnapshot = {
   projectId: string;
   title: string;
+  canvas?: EditorCanvasSnapshot;
   viewport: EditorCanvasViewport;
   layers: EditorProjectLayerSnapshot[];
   resources: EditorProjectResourceSnapshot[];
   updatedAt: string;
 };
 
+export type EditorCanvasSnapshot = {
+  canvasId: string;
+  projectId: string;
+  title: string;
+  viewport: EditorCanvasViewport;
+  layers: EditorProjectLayerSnapshot[];
+  createdAt?: string;
+  updatedAt: string;
+};
+
 export type EditorProjectCreateInput = {
   title?: string;
 };