fix(server): limit rootDoc snapshot size (#12625)

close CLOUD-225

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- **New Features**
  - Added support for reading document blocks without requiring a workspace or root document snapshot.
- **Bug Fixes**
  - Improved handling of large workspace snapshots by skipping them when they exceed 10MB.
- **Tests**
  - Introduced new test cases to cover scenarios where root or workspace snapshots are absent.
  - Expanded snapshot tests for document block reading.
- **Refactor**
  - Updated several function signatures to make root and workspace snapshot parameters optional for greater flexibility.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/common/reader/src/reader.ts

@@ -59,9 +59,9 @@ const bookmarkFlavours = new Set([
 ]);
 
 function generateMarkdownPreviewBuilder(
-  yRootDoc: YDoc,
   workspaceId: string,
-  blocks: BlockDocumentInfo[]
+  blocks: BlockDocumentInfo[],
+  yRootDoc?: YDoc
 ) {
   function yblockToDraftModal(yblock: YBlock): DraftModel | null {
     const flavour = yblock.get('sys:flavour') as string;
@@ -91,7 +91,7 @@ function generateMarkdownPreviewBuilder(
   }
 
   const titleMiddleware: TransformerMiddleware = ({ adapterConfigs }) => {
-    const pages = yRootDoc.getMap('meta').get('pages');
+    const pages = yRootDoc?.getMap('meta').get('pages');
     if (!(pages instanceof YArray)) {
       return;
     }
@@ -442,7 +442,7 @@ export async function readAllBlocksFromDoc({
   maxSummaryLength,
 }: {
   ydoc: YDoc;
-  rootYDoc: YDoc;
+  rootYDoc?: YDoc;
   spaceId: string;
   maxSummaryLength?: number;
 }): Promise<
@@ -459,9 +459,9 @@ export async function readAllBlocksFromDoc({
   const blockDocuments: BlockDocumentInfo[] = [];
 
   const generateMarkdownPreview = generateMarkdownPreviewBuilder(
-    rootYDoc,
     spaceId,
-    blockDocuments
+    blockDocuments,
+    rootYDoc
   );
 
   const blocks = ydoc.getMap<any>('blocks');