GCP Onboarding

When implementing changes that affect environment setup, inspect and maintain:

• docs/guidelines/gcp-onboarding.md
• projects/frontend/README.md
• projects/backend/README.md
• .github/copilot-instructions.md

Keep onboarding docs concise and task-oriented. Prefer checklists, exact config names, and copy-pasteable commands. Avoid duplicating the full guide in multiple READMEs; link to docs/guidelines/gcp-onboarding.md from local setup sections.

Required checks:

1. If OAuth origins, scopes, consent screen requirements, Google APIs, environment flags, secrets, Cloud Run settings, or deployment commands changed, update docs/guidelines/gcp-onboarding.md.
2. If the setup change is not straightforward enough to document safely, add a short note in the PR or implementation summary that onboarding docs need confirmation.
3. Keep existing documentation and links intact unless they are stale.
4. Never include real secrets, private client secrets, or production-only secret values in documentation.