gittensor-impact.yml and visual-capture-fallback.yml hardcode a Node version instead of reading .nvmrc despite checking out the repo first

[JSONbored]

Context

Every workflow in .github/workflows/** that installs Node uses
actions/setup-node's node-version-file: .nvmrc — confirmed across ci.yml, audit.yml,
upstream-contract.yml, all four publish-*.yml files, stuck-check-watchdog.yml,
test-timing-refresh.yml, ci-duration-report.yml, mcp-release-watch.yml, mcp-ui-version-sync.yml,
and more — except three, which hardcode a literal patch version instead:

.github/workflows/gittensor-impact.yml:39:          node-version: 22.23.1
.github/workflows/ui-preview-deploy.yml:70:          node-version: "22.23.1"
.github/workflows/visual-capture-fallback.yml:101:          node-version: "22.23.1"

ui-preview-deploy.yml's hardcoded value carries a comment explaining why and claims the same reason
applies to the other two:

Hardcoded, NOT node-version-file: .nvmrc -- this job deliberately has no checkout step (see the
file header), so there is no .nvmrc on the runner to read. Keep this in sync with .nvmrc's pinned
version by hand; same exception already established for gittensor-impact.yml and
visual-capture-fallback.yml.

That reasoning is genuinely true for ui-preview-deploy.yml's own job (its Setup Node step has no
prior Checkout step in that job). It is not true for the other two: both gittensor-impact.yml
(publish job: Checkout → Setup Node) and visual-capture-fallback.yml (Checkout PR head →
Setup Node) run actions/checkout before Setup Node, so .nvmrc is present on the runner in both
cases — there is no structural reason for them to hardcode instead of reading it, unlike
ui-preview-deploy.yml.

Concretely, this means two of the three hardcodes are unnecessary manual-sync burdens with a real drift
risk: scripts/check-engines-nvmrc-sync.ts's own header comment states "CI itself was never at risk"
of a Node-version mismatch specifically because .github/actions/setup-workspace (used by most
workflows) pins node-version-file: .nvmrc — but that guarantee doesn't extend to these three
directly-hardcoded workflows, and nothing catches it if .nvmrc's major is bumped in the future and
these three are forgotten (they were: the comment already admits "keep in sync ... by hand").

Requirements

• In .github/workflows/gittensor-impact.yml's publish job, replace the hardcoded
  node-version: 22.23.1 on the Setup Node step with node-version-file: .nvmrc (the Checkout step
  already runs first in that job, so .nvmrc is present).
• In .github/workflows/visual-capture-fallback.yml, replace the hardcoded node-version: "22.23.1"
  on the Setup Node step with node-version-file: .nvmrc (the Checkout PR head step already runs
  first in that job).
• Do not change .github/workflows/ui-preview-deploy.yml — its job genuinely has no checkout step,
  so its hardcoded value is structurally necessary and must stay.
• Update ui-preview-deploy.yml's own comment (the one quoted in Context above) so it no longer cites
  gittensor-impact.yml/visual-capture-fallback.yml as sharing its "no checkout step" reasoning,
  since after this fix they won't share that reasoning anymore — reword it to state plainly that this
  job is the only one in the repo with this exception, and why.

Deliverables

• .github/workflows/gittensor-impact.yml: node-version-file: .nvmrc instead of a hardcoded
  version.
• .github/workflows/visual-capture-fallback.yml: node-version-file: .nvmrc instead of a
  hardcoded version.
• .github/workflows/ui-preview-deploy.yml's comment updated to no longer claim the other two
  workflows share its no-checkout justification.

Test Coverage Requirements

This is a .github/workflows/**-only change; neither .github/** nor scripts/** is in Codecov's
coverage.include (codecov.yml), so there is no codecov/patch obligation. Verification is:
npm run actionlint passes on both edited workflow files, and a visual diff confirming the only
functional change is the Setup Node with: block (no other step reordering).

Expected Outcome

Only one workflow in the repo (ui-preview-deploy.yml, which structurally cannot do otherwise) still
hardcodes a Node patch version; the other two follow every other workflow's .nvmrc-derived pattern and
can never silently drift from it again.

Links & Resources

• .github/workflows/gittensor-impact.yml (line ~39, publish job)
• .github/workflows/visual-capture-fallback.yml (line ~101)
• .github/workflows/ui-preview-deploy.yml (line ~70, the comment to reword — this file itself is NOT
  changed functionally)
• scripts/check-engines-nvmrc-sync.ts (header comment establishing the "CI is never at risk" premise
  this issue narrows the exception to actually match)
• .nvmrc (the source of truth these workflows should follow)

[linear-code]

JSO-5893