Fix release pnpm runtime on main

[Obed0101]

Problem

Prerelease runs invoke the reusable Release workflow definition from main. The Blacksmith Linux runner exposes Node 20.20.0 to shell steps, while pnpm 11.0.9 requires Node >=22.13 and fails loading node:sqlite.

Solution

Provision pinned Node 24 before pnpm in all three release builders (Linux, Windows, Darwin). This mirrors the existing stable-startup workflow and keeps runner images from deciding pnpm compatibility.

Evidence

• prerelease runs 34811242134 and 34812034889 failed with ERR_UNKNOWN_BUILTIN_MODULE: node:sqlite under Node 20.20.0
• second run checked out corrected dev source but omitted Setup Node, proving the reusable workflow definition came from main
• bash .github/scripts/supply-chain-preflight.sh passed
• git diff --check origin/main...HEAD passed

Scope

One workflow file, 15 added lines. No beta application code is promoted to main.

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