fix(ci): restore main Telegram RTT packaging

[steipete]

What Problem This Solves

Fixes Main RTT stopping before Telegram measurements when packaging validates native dependencies in the generated npm lockfile.

User Impact

Restores main-branch Telegram timing collection without relaxing OpenClaw's native-platform checks.

Why This Change Was Made

pnpm/setup installs a runtime-only Node distribution. Packaging could therefore fall back to the runner's older npm, which omits libc constraints. Install the complete Node/npm toolchain after pnpm setup, using the existing Node version. Add an ordering regression test and document the packaging requirement.

Evidence

• Original failure: https://github.com/openclaw/openclaw-rtt/actions/runs/38010496187
• Minimal native-package reproduction: npm 10.8.2 drops libc: ["glibc"]; npm 11.20.0 (bundled with Node 26.11.1) and npm 12.2.0 preserve it.
• New workflow regression test fails before the change and passes after it.
• npm run check, all 232 script tests (two workers), and actionlint pass.
• Independent Codex autoreview: no actionable P0–P2 findings.
• Crabbox reported fleet capacity (21/20); the light repository gate ran locally under nice -n 19.