docs: add DSC setup scripts and comprehensive release process guide

- Add scripts/setup-release.sh (bash, all scopes + token types, idempotent)
- Add scripts/setup-release.ps1 (PowerShell DSC, all scopes + token types, idempotent)
- Rewrite docs/release-process.md with full scope/token matrix, script reference,
  manual setup guide (all 4 scopes × 3 token types), ruleset CLI commands,
  GHES notes, and expanded troubleshooting
- Update wiki Contributing.md to reference DSC scripts

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: kieronlanning