v1.12.0 — service security scan, port-forward demo, CVE gating

- Security risks: static analyzers over each service spec flag containers
  pinned to root and credentials embedded in environment variables. A
  leading 🛡 marks a flagged service in the tree; '!' opens an overlay
  listing every finding by severity. Only an env var's key name is ever
  shown, never its value. The analyzer set is an extensible registry.
- Site: a second demo slide showing port-forwarding, in a two-slide
  carousel next to the existing demo.
- Security: fixed two reachable CVEs (grpc 1.82.1, x/text 0.39.0) and
  added a govulncheck CI stage that fails a build on a reachable
  vulnerability with an available fix.
- Docs: the security scan documented and drifted docs corrected
  (logfmt, the L logs key, ? / --ssh-jump / SWARMEXEC_KEYS, keys.yaml) in
  all four languages.