feat(server): page model (#9715)

packages/backend/server/src/models/common/index.ts

@@ -1,2 +1,3 @@
 export * from './feature';
+export * from './page';
 export * from './permission';

packages/backend/server/src/models/common/page.ts

@@ -0,0 +1,4 @@
+export enum PublicPageMode {
+  Page,
+  Edgeless,
+}