The argocd plugin uses pnpm (packageManager: pnpm@10.32.1) but the
inline workflow was using npm-based commands (npm ci, cache: npm).
This caused 'Setup Node.js' to fail because setup-node@v6 with
cache: npm has issues when no package-lock.json exists.
Switch to the reusable plugin-e2e workflow which properly detects
and uses pnpm for projects with pnpm-lock.yaml.
Fixes PRI-524. Changes push trigger from branches:[main] to branches:['**'] so CI fires on every branch. Adds workflow_dispatch for manual trigger. Adds permissions: contents: read for least-privilege hardening.
All gates clear: CI green, UAT correctly skipped (YAML-only), QA approved (Regina), CTO approved (Nancy).