Add SMTP configuration to Grafana for alert emails

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infrastructure/docker-compose.yml

@@ -155,6 +155,12 @@ services:
       GF_AUTH_GITHUB_ALLOWED_ORGANIZATIONS: trails-cool
       GF_AUTH_GITHUB_SCOPES: user:email,read:org
       GF_AUTH_DISABLE_LOGIN_FORM: "true"
+      GF_SMTP_ENABLED: "true"
+      GF_SMTP_HOST: ${GF_SMTP_HOST:-}
+      GF_SMTP_USER: ${GF_SMTP_USER:-}
+      GF_SMTP_PASSWORD: ${GF_SMTP_PASSWORD:-}
+      GF_SMTP_FROM_ADDRESS: noreply@trails.cool
+      GF_SMTP_FROM_NAME: trails.cool Grafana
       GRAFANA_DB_PASSWORD: ${GRAFANA_DB_PASSWORD:-}
     volumes:
       - ./grafana/provisioning:/etc/grafana/provisioning:ro