feat: improve mobile native impl (#14481)

fix #13529 

#### PR Dependency Tree


* **PR #14481** 👈

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**
* Mobile blob caching with file-backed storage for faster loads and
reduced network usage
* Blob decoding with lazy refresh on token-read failures for improved
reliability
  * Full-text search/indexing exposed to mobile apps
* Document sync APIs and peer clock management for robust cross-device
sync

* **Tests**
* Added unit tests covering payload decoding, cache safety, and
concurrency

* **Dependencies**
* Added an LRU cache dependency and a new mobile-shared package for
shared mobile logic
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/android/src/plugins/nbstore/definitions.ts

@@ -2,7 +2,7 @@ import type { CrawlResult, DocIndexedClock } from '@affine/nbstore';
 
 export interface Blob {
   key: string;
-  // base64 encoded data
+  // base64 encoded data, or "__AFFINE_BLOB_FILE__:<absolutePath>" for large blobs
   data: string;
   mime: string;
   size: number;
@@ -41,6 +41,7 @@ export interface NbStorePlugin {
   pushUpdate: (options: {
     id: string;
     docId: string;
+    // base64 encoded data
     data: string;
   }) => Promise<{ timestamp: number }>;
   getDocSnapshot: (options: { id: string; docId: string }) => Promise<
@@ -55,6 +56,7 @@ export interface NbStorePlugin {
   setDocSnapshot: (options: {
     id: string;
     docId: string;
+    // base64 encoded data
     bin: string;
     timestamp: number;
   }) => Promise<{ success: boolean }>;

packages/frontend/apps/android/src/plugins/nbstore/index.ts

@@ -2,6 +2,10 @@ import {
   base64ToUint8Array,
   uint8ArrayToBase64,
 } from '@affine/core/modules/workspace-engine';
+import {
+  decodePayload,
+  MOBILE_BLOB_FILE_PREFIX,
+} from '@affine/mobile-shared/nbstore/payload';
 import {
   type BlobRecord,
   type CrawlResult,
@@ -132,14 +136,23 @@ export const NbStoreNativeDBApis: NativeDBApis = {
       id,
       key,
     });
-    return record
-      ? {
-          data: base64ToUint8Array(record.data),
-          key: record.key,
-          mime: record.mime,
-          createdAt: new Date(record.createdAt),
-        }
-      : null;
+    if (!record) {
+      return null;
+    }
+
+    let refreshedBlobPromise: ReturnType<typeof NbStore.getBlob> | undefined;
+
+    return {
+      data: await decodePayload(record.data, MOBILE_BLOB_FILE_PREFIX, {
+        onTokenReadFailure: async () => {
+          refreshedBlobPromise ??= NbStore.getBlob({ id, key });
+          return (await refreshedBlobPromise)?.data;
+        },
+      }),
+      key: record.key,
+      mime: record.mime,
+      createdAt: new Date(record.createdAt),
+    };
   },
   setBlob: async function (id: string, blob: BlobRecord): Promise<void> {
     await NbStore.setBlob({