Remove GCP deployment infrastructure

[anth-volk]

Fixes #392

Summary

• Removes all GCP Cloud Run deployment infrastructure (Terraform, workflows, scripts)
• Removes policyengine-api-full and policyengine-api-tagger projects (GCP-exclusive)
• Updates remaining workflows and scripts to be Modal-only
• Removes GCP-specific integration tests

Changes

Deleted

• .github/workflows/deploy.yml, gcp-build.reusable.yml, gcp-deploy.reusable.yml
• deployment/terraform/ (entire directory)
• projects/policyengine-api-full/ (entire directory)
• projects/policyengine-api-tagger/ (entire directory)
• GCP-specific scripts (cleanup_old_revisions.py, restore-tags-from-backup.sh, update-deployments-manifest.sh)
• GCP-specific tests (tests/full/, tests/tagger/, tests/simulation_workflow/)
• Cloud Workflow definition (workflow.yaml)
• Deployment docs and configs (cloudbuild.yaml, init-gcp.sh, .env.example, etc.)

Updated

• publish-clients.yml - Now triggers on Modal deploy, only publishes simulation client
• pr.yml - Tests only api-simulation service
• generate-clients.sh - Generates only simulation client
• docker-compose.yml - Contains only api-simulation service
• policyengine-apis-integ/pyproject.toml - Removed full API client and GCP dependencies

Test plan

• Verify PR checks pass (tests, lint, Docker build)
• Verify Modal deployment workflow still works
• Verify client publishing workflow triggers correctly after Modal deploy

🤖 Generated with Claude Code