test(sagemaker): add HyperPod integration tests and WriteQueue unit test

Integration tests cover:
- Deeplink connection flow (prepare → launch IDE)
- Side panel (LC) connection flow
- Space lifecycle (start/stop/connect-to-stopped)
- Server routes with real HTTP (/get_hyperpod_session, /get_hyperpod_session_async)
- Multi-IDE support (VS Code, Cursor, Kiro)

Unit test added for WriteQueue sequential write serialization.

Author: aws-ajangg

packages/core/src/test/awsService/sagemaker/detached-server/writeQueue.test.ts

@@ -0,0 +1,61 @@
+/*!
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import assert from 'assert'
+import { WriteQueue } from '../../../../awsService/sagemaker/detached-server/writeQueue'
+
+describe('WriteQueue', function () {
+    it('processes operations sequentially', async function () {
+        const queue = new WriteQueue()
+        const order: number[] = []
+
+        queue.push(async () => {
+            await new Promise((r) => setTimeout(r, 10))
+            order.push(1)
+        })
+        queue.push(async () => {
+            order.push(2)
+        })
+        queue.push(async () => {
+            order.push(3)
+        })
+
+        await queue.process()
+
+        assert.deepStrictEqual(order, [1, 2, 3])
+    })
+
+    it('concurrent process() calls do not duplicate work', async function () {
+        const queue = new WriteQueue()
+        let count = 0
+
+        queue.push(async () => {
+            await new Promise((r) => setTimeout(r, 10))
+            count++
+        })
+
+        // Call process twice simultaneously
+        await Promise.all([queue.process(), queue.process()])
+
+        assert.strictEqual(count, 1)
+    })
+
+    it('can enqueue after previous batch completes', async function () {
+        const queue = new WriteQueue()
+        const results: string[] = []
+
+        queue.push(async () => {
+            results.push('first')
+        })
+        await queue.process()
+
+        queue.push(async () => {
+            results.push('second')
+        })
+        await queue.process()
+
+        assert.deepStrictEqual(results, ['first', 'second'])
+    })
+})