GitHub Actions CI/CD pipeline

[troyscott]

Description

Automated build, test, and deploy pipeline via GitHub Actions.

Workflows

• ci.yml — On PR: lint, type-check, test
• deploy-infra.yml — On merge to main: deploy infra changes
• deploy-app.yml — On merge to main: build and deploy app
• teardown.yml — Manual trigger: tear down environment

Acceptance criteria

• CI runs on every PR
• Infra deploys on merge (Bicep)
• App deploys on merge (zip deploy)
• Manual teardown workflow
• GitHub environments for dev/staging/prod
• OIDC auth to Azure (no stored secrets)