[ci-scan] Test failure: ZipArchive DirectToArchiveWriterStream.ThrowIfDisposed NullReferenceException in async zip_CreateTests ( [Content truncated due to length]

## Build Information
Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1573717
Build error leg or test failing: linux-x64 Release (azurelinux.3.amd64.open.rt) — System.IO.Compression.Tests

Pipeline: `runtime-coreclr libraries-pgo` (definition 145), branch `main`. Under the PGO stress configuration, `System.IO.Compression.Tests` async ZIP-create tests throw `System.NullReferenceException` inside `ZipArchiveEntry.DirectToArchiveWriterStream.ThrowIfDisposed()` (ZipArchiveEntry.cs line 2275), reached from the async `WriteAsync` write path via `ZipFileTestBase.CreateFromDir`. Affected tests include `zip_CreateTests.CreateNormal_Unseekable_CompareSyncAndAsync` and `zip_CreateTests.CreateNormal_Seekable(..., async: True)`. Reproduces on the linux-x64 and linux-arm64 Release legs across source build 1573717 and follow-up build 1574201.

## Error Details

```
System.IO.Compression.Tests.zip_CreateTests.CreateNormal_Unseekable_CompareSyncAndAsync(folder: "normal") [FAIL]
System.NullReferenceException : Object reference not set to an instance of an object.
at System.IO.Compression.ZipArchiveEntry.DirectToArchiveWriterStream.ThrowIfDisposed() ZipArchiveEntry.cs(2275,0)
at System.IO.Compression.ZipArchiveEntry.DirectToArchiveWriterStream.WriteAsync(ReadOnlyMemory`1 buffer, CancellationToken cancellationToken) ZipArchiveEntry.cs(2370,0)
at System.IO.Compression.Tests.ZipFileTestBase.CreateFromDir(...) ZipTestHelper.cs(477,0)
at System.IO.Compression.Tests.zip_CreateTests.CreateNormal_Unseekable_CompareSyncAndAsync(String folder) zip_CreateTests.cs(182,0)
```

## Error Message

```json
{
"ErrorMessage": [
"System.IO.Compression.Tests.zip_CreateTests.CreateNormal",
"System.NullReferenceException",
"DirectToArchiveWriterStream.ThrowIfDisposed()"
],
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

Agentic workflow metadata (ci-failure-scan)

Workflow artifact: ci-failure-scan
Artifact kind: kbe-verification
Verified match count: 2 hits in failure.log

## First build it occurred
Source build [1573717](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1573717); reproduces in follow-up build [1574201](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1574201) on the linux-x64 and linux-arm64 Release legs.

## Duplicate search
Searched open/closed `Known Build Error` issues and PRs for `DirectToArchiveWriterStream`, `ThrowIfDisposed`, and the `zip_CreateTests` async NRE. Related dotnet/runtime#129813 was a runtime-async tail-call miscompile NRE (different call site, not this ZIP write path). No open `Known Build Error` matches this `DirectToArchiveWriterStream.ThrowIfDisposed` NRE under libraries-pgo.

---
Filed by [`ci-failure-scan`](https://github.com/dotnet/runtime/blob/main/.github/workflows/ci-failure-scan.md) (detection only). [`ci-failure-fix`](https://github.com/dotnet/runtime/blob/main/.github/workflows/ci-failure-fix.md) walks open `[ci-scan]` KBEs and either opens a small fix PR or comments to loop in owners — it never disables the test.

> [!NOTE]
> Generated by the CI Outer-Loop Failure Scanner agentic workflow.

> Generated by [CI Outer-Loop Failure Scanner](https://github.com/dotnet/runtime/actions/runs/33509302092) · opus48 · 776.4 AIC · ⌖ 16.1 AIC · ⊞ 20.7K · [◷](https://github.com/search?q=repo%3Adotnet%2Fruntime+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fruntime%2Fci-failure-scan%22&type=issues)

### Report

|Build|Repository|Test|Pull Request|
|---|---|---|---|
|[1584906](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1584906)|dotnet/runtime|[System.IO.Compression.Tests.zip_CreateTests.CreateNormal_Seekable](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1584906&view=ms.vss-test-web.build-test-results-tab&runId=43731396&resultId=172513)||
|[1584422](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1584422)|dotnet/runtime|[System.IO.Compression.Tests.zip_CreateTests.CreateNormal_Seekable](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1584422&view=ms.vss-test-web.build-test-results-tab&runId=43716152&resultId=138824)||
|[1579855](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1579855)|dotnet/runtime|[System.IO.Compression.Tests.zip_CreateTests.CreateNormal_Seekable](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1579855&view=ms.vss-test-web.build-test-results-tab&runId=43574454&resultId=143350)||
|[1574201](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1574201)|dotnet/runtime|[System.IO.Compression.Tests.zip_CreateTests.CreateNormal_Seekable](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1574201&view=ms.vss-test-web.build-test-results-tab&runId=43380766&resultId=138358)||
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|0|0|4|