WARNING: The following characters are invalid in Windows file and directory names: /:*?"<>| when using gcloud storage cp

When using `gcloud storage cp --recursive "gs://some-bucket/orgs" .` on Windows, the copy operation of some (random) files fail with the following errors even though my file paths are not using any of the invalid characters on Windows:
```
WARNING: The following characters are invalid in Windows file and directory names: /:*?"<>|
Renaming \\?\C:\some\dir\data\123\456\some\data\123-abc-456-xyz_.gstmp to \\$3\C$1\some\dir\data\123\456\some\data\123-abc-456-xyz_.gstmpERROR: Task 'file://.\\data\\123\\456\\some\\data\\123-abc-456-xyz' failed: FileNotFoundError(2, 'The network path was not found.')
```

This causes these files to be missing from the copy operation.

I'm using the following versions:
```
Google Cloud SDK 566.0.0
bq 2.1.31
core 2026.04.24
gcloud-crc32c 1.0.0
gsutil 5.36
```

Start with the `gcloud storage cp --recursive` command on Windows using the versions reported in the issue, and reproduce the failed copy and rename. Trace the handling of the temporary `.gstmp` path and Windows filename validation; done means all files copy successfully without the invalid-character warning or FileNotFoundError.

Written by the indexing model from the issue text.