Initial development of ucam-minimal-gcp-monitoring module

Summary

This initial issue covers the following tasks:

1. Deploy the terraform-module-boilerplate copier template and update any template sections as required.
2. Add initial alert policies from the gcp-cloud-run-app module:
   • Existing load balancer server errors alert.
   • Proposed memory exceedance alert for Cloud Run services.
3. Document this module, both in the local ./docs/examples.md and a section in the guidebook explaining what it is.

Background

Previously, we've experimented with alert configurations being included within other Terraform modules such as the gcp-cloud-run-app module. This approach has proved cumbersome, so we're moving towards centralising our monitoring and alerting logic within this new, opinionated module.

This module will be integrated into the gcp-deploy-boilerplate and will serve as the main place to define alerting for standard Unified Platform deployments.

This centralisation also positions us to better manage the upcoming changes to Google’s Monitoring pricing model, where alert policy conditions will become chargeable from May 2026. The goal is to define our monitoring and alerting resources in a cost-effective manner while ensuring full compliance with the University’s Systems Management Policy (SMP) for monitoring.