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 -->

Author: fengmk2

packages/backend/server/src/core/utils/__tests__/__snapshots__/blocksute.spec.ts.md

@@ -45,7 +45,23 @@ test('can read all blocks from doc snapshot', async t => {
 
   const result = await readAllBlocksFromDocSnapshot(
     workspace.id,
-    rootDoc!.blob,
+    'doc-0',
+    docSnapshot.blob,
+    rootDoc!.blob
+  );
+
+  t.snapshot({
+    ...result,
+    blocks: result!.blocks.map(block => omit(block, ['yblock'])),
+  });
+});
+
+test('can read all blocks from doc snapshot without workspace snapshot', async t => {
+  const doc = await models.doc.get(workspace.id, docSnapshot.id);
+  t.truthy(doc);
+
+  const result = await readAllBlocksFromDocSnapshot(
+    workspace.id,
     'doc-0',
     docSnapshot.blob
   );

packages/backend/server/src/core/utils/__tests__/__snapshots__/blocksute.spec.ts.snap

@@ -173,15 +173,18 @@ export function readAllDocIdsFromWorkspaceSnapshot(snapshot: Uint8Array) {
 
 export async function readAllBlocksFromDocSnapshot(
   workspaceId: string,
-  workspaceSnapshot: Uint8Array,
   docId: string,
   docSnapshot: Uint8Array,
+  workspaceSnapshot?: Uint8Array,
   maxSummaryLength?: number
 ) {
-  const rootYDoc = new YDoc({
-    guid: workspaceId,
-  });
-  applyUpdate(rootYDoc, workspaceSnapshot);
+  let rootYDoc: YDoc | undefined;
+  if (workspaceSnapshot) {
+    rootYDoc = new YDoc({
+      guid: workspaceId,
+    });
+    applyUpdate(rootYDoc, workspaceSnapshot);
+  }
   const ydoc = new YDoc({
     guid: docId,
   });

packages/backend/server/src/core/utils/__tests__/blocksute.spec.ts

@@ -226,11 +226,14 @@ export class IndexerService {
       this.logger.debug(`doc ${workspaceId}/${docId} is empty, skip indexing`);
       return;
     }
+    const MAX_WORKSPACE_SNAPSHOT_SIZE = 1024 * 1024 * 10; // 10MB
     const result = await readAllBlocksFromDocSnapshot(
       workspaceId,
-      workspaceSnapshot.blob,
       docId,
-      docSnapshot.blob
+      docSnapshot.blob,
+      workspaceSnapshot.blob.length < MAX_WORKSPACE_SNAPSHOT_SIZE
+        ? workspaceSnapshot.blob
+        : undefined
     );
     if (!result) {
       this.logger.warn(