security: fix CVE-2026-39836 [1.26 backport]

[gopherbot]

@thatnealpatel requested issue #79006 to be considered for backport to the next 1.26 minor release.

Hi @gopherbot, please open backport issues for this security issue.

[gopherbot]

Change https://go.dev/cl/775162 mentions this issue: [release-branch.go1.26] all: avoid unsafe StringToUTF16Ptr on Windows

[gopherbot]

Closed by merging CL 775162 (commit 3baf3ee) to release-branch.go1.26.