docs(security): sync SECURITY.md Supply Chain Trust with runbook v1.2 template #13

Job	Run time
Scan pinned upstream image with Trivy (postgres, postgres:16@sha256:71e27bf60b70bded003791b5573f8...	23s
Lint shell scripts and workflow YAML	5s
Scan pinned upstream image with Trivy (traefik, traefik:3.2@sha256:e561a37f8710d9cf41c78bdf421d82...	24s
Scan pinned upstream image with Trivy (keycloak, quay.io/keycloak/keycloak:26.2.5@sha256:4883630e...	44s
docker compose up + HTTPS + Traefik dashboard smoke	58s
	2m 34s

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