feat(server): search blob names from indexer (#12822)

#### PR Dependency Tree


* **PR #12822** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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

- **New Features**
- Added the ability to search for blob names by their IDs within a
workspace.
- **Tests**
- Introduced new test cases and snapshot tests to validate searching
blob names and reading filenames from document snapshots.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/indexer/service.ts

@@ -387,6 +387,52 @@ export class IndexerService {
     await searchProvider.deleteByQuery(table, dsl, options);
   }
 
+  async searchBlobNames(workspaceId: string, blobIds: string[]) {
+    const result = await this.search({
+      table: SearchTable.block,
+      query: {
+        type: SearchQueryType.boolean,
+        occur: SearchQueryOccur.must,
+        queries: [
+          {
+            type: SearchQueryType.match,
+            field: 'workspaceId',
+            match: workspaceId,
+          },
+          {
+            type: SearchQueryType.match,
+            field: 'flavour',
+            match: 'affine:attachment',
+          },
+          {
+            type: SearchQueryType.boolean,
+            occur: SearchQueryOccur.should,
+            queries: blobIds.map(blobId => ({
+              type: SearchQueryType.match,
+              field: 'blob',
+              match: blobId,
+            })),
+          },
+        ],
+      },
+      options: {
+        fields: ['blob', 'content'],
+        pagination: {
+          limit: 10000,
+        },
+      },
+    });
+    const blobNameMap = new Map<string, string>();
+    for (const node of result.nodes) {
+      const blobId = node.fields.blob[0] as string;
+      const content = node.fields.content[0] as string;
+      if (blobId && content) {
+        blobNameMap.set(blobId, content);
+      }
+    }
+    return blobNameMap;
+  }
+
   #formatSearchNodes(nodes: SearchNode[]) {
     return nodes.map(node => ({
       ...node,