feat(server): lightweight s3 client (#14348)

#### PR Dependency Tree


* **PR #14348** 👈

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 a dedicated S3-compatible client package and expanded
S3-compatible storage config (endpoint, region, forcePathStyle,
requestTimeoutMs, minPartSize, presign options, sessionToken).
* Document sync now broadcasts batched/compressed doc updates for more
efficient real-time syncing.

* **Tests**
* New unit and benchmark tests for base64 utilities and S3 multipart
listing; updated storage-related tests to match new formats.

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

packages/common/nbstore/src/__tests__/base64.bench.ts

@@ -0,0 +1,23 @@
+import { bench, describe } from 'vitest';
+
+import { base64ToUint8Array, uint8ArrayToBase64 } from '../impls/cloud/socket';
+
+const data = new Uint8Array(1024 * 256);
+for (let i = 0; i < data.length; i++) {
+  data[i] = i % 251;
+}
+let encoded = '';
+
+await uint8ArrayToBase64(data).then(result => {
+  encoded = result;
+});
+
+describe('base64 helpers', () => {
+  bench('encode Uint8Array to base64', async () => {
+    await uint8ArrayToBase64(data);
+  });
+
+  bench('decode base64 to Uint8Array', () => {
+    base64ToUint8Array(encoded);
+  });
+});

packages/common/nbstore/src/__tests__/base64.spec.ts

@@ -0,0 +1,27 @@
+import { describe, expect, test } from 'vitest';
+
+import { base64ToUint8Array, uint8ArrayToBase64 } from '../impls/cloud/socket';
+
+function makeSample(size: number) {
+  const data = new Uint8Array(size);
+  for (let i = 0; i < size; i++) {
+    data[i] = i % 251;
+  }
+  return data;
+}
+
+describe('base64 helpers', () => {
+  test('roundtrip preserves data', async () => {
+    const input = makeSample(1024);
+    const encoded = await uint8ArrayToBase64(input);
+    const decoded = base64ToUint8Array(encoded);
+    expect(decoded).toEqual(input);
+  });
+
+  test('handles large payloads', async () => {
+    const input = makeSample(256 * 1024);
+    const encoded = await uint8ArrayToBase64(input);
+    const decoded = base64ToUint8Array(encoded);
+    expect(decoded).toEqual(input);
+  });
+});

packages/common/nbstore/src/__tests__/cloud-doc-updates.spec.ts

@@ -0,0 +1,41 @@
+import { describe, expect, test } from 'vitest';
+
+import { CloudDocStorage } from '../impls/cloud/doc';
+
+const base64UpdateA = 'AQID';
+const base64UpdateB = 'BAUG';
+
+describe('CloudDocStorage broadcast updates', () => {
+  test('emits updates from batch payload', () => {
+    const storage = new CloudDocStorage({
+      id: 'space-1',
+      serverBaseUrl: 'http://localhost',
+      isSelfHosted: true,
+      type: 'workspace',
+      readonlyMode: true,
+    });
+
+    (storage as any).connection.idConverter = {
+      oldIdToNewId: (id: string) => id,
+      newIdToOldId: (id: string) => id,
+    };
+
+    const received: Uint8Array[] = [];
+    storage.subscribeDocUpdate(update => {
+      received.push(update.bin);
+    });
+
+    storage.onServerUpdates({
+      spaceType: 'workspace',
+      spaceId: 'space-1',
+      docId: 'doc-1',
+      updates: [base64UpdateA, base64UpdateB],
+      timestamp: Date.now(),
+    });
+
+    expect(received).toEqual([
+      new Uint8Array([1, 2, 3]),
+      new Uint8Array([4, 5, 6]),
+    ]);
+  });
+});