Skip validate-release on smoke builds

[ptr727]

Problem

Closes #219. The validate-release entry gate (added in #213/#215) runs unconditionally, including in PR smoke builds. A smoke build checks out the PR head in detached HEAD, so NBGV always computes a prerelease version (X.Y.Z-g<sha>). On a main-base PR — a develop → main promotion carrying a build target — the gate's branch == 'main' arm fails:

::error::Public (main) release version 'X.Y.Z-g<sha>' carries a prerelease suffix; refusing to publish.

validate-release fails → build is skipped → the required Check pull request workflow status fails. Every clean develop → main promotion PR that includes a build-target change is blocked by its own smoke build (masked only when merged via admin bypass).

Fix

Skip the gate for smoke builds — they never publish — keeping the job in the graph as a success so build-*'s needs: [get-version, validate-release] stays satisfied:

          SMOKE: ${{ inputs.smoke }}
          ...
          if [[ "$SMOKE" == "true" ]]; then
            echo "Smoke build; skipping release version validation."
            exit 0
          fi

Real publishes (smoke: false) still get both-direction validation.

Verification

• actionlint (Docker, shellcheck-bundled) clean; CRLF preserved.
• Per the issue's push-probe: a smoke: true invocation passes for both branch: main (Release) and branch: develop (Debug) with github-release skipped; real publishes unaffected.

Found via end-to-end CI flow validation during the #213/#214 downstream re-sync.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adjusts the reusable release build workflow so the validate-release entry gate does not fail PR smoke builds (which run in detached HEAD and therefore always produce an NBGV prerelease SemVer2), unblocking clean develop -> main promotion PRs that include build-target changes.

Changes:

• Passes inputs.smoke into the validate-release step via SMOKE env var.
• Early-exits the validate-release script successfully when running in smoke mode, while keeping the job in the DAG so dependent build jobs' needs: remain satisfied.