Restore stable 9.4 versioning on release/9.x

[dwcullop]

Problem

release/9.x cannot publish. PR #1088 overwrote this branch''s version.json with main''s preview line, so HEAD declares "version": "9.5-preview.{height}". NBGV computes 9.5.0-preview.2, and the policy step in release.yml refuses to publish a prerelease from a release/*.x branch, so the branch is stuck.

Fix

Restore the stable form. This branch ships stable 9.4.x, and the latest published version (the tag on this repo and the package on NuGet.org) is 9.4.31:

"version": "9.4",
"versionHeightOffset": 31,

The base-version flip 9.4 -> 9.5 -> 9.4 resets NBGV''s git height to 1 on the commit that re-introduces 9.4, so the offset is required to keep the patch number continuous.

Verification

nbgv get-version, evaluated on the post-merge topology (one commit on the current HEAD, on a release/9.x ref):

Field	Value
SemVer2	9.4.32
PrereleaseVersion	(empty)
PublicRelease	True

Next publish is a clean stable 9.4.32, continuing from 9.4.31. Offset 31 is the minimum safe value; 30 would compute 9.4.31 and collide with the existing release.

Label

Labeled manual-version-edit so pr-version-check.yml permits the hand edit. This is the recovery case the label is documented for.