Replaces the presence-only `grep -qi strict-transport-security` smoke
assertion in both nightly.yml and release.yml with a value-pinning
regex that requires `max-age=31536000`, `includeSubDomains`, and
`preload`. A future Caddyfile edit that drops any of those three
parts now fails the deploy smoke step instead of passing silently.
Verified locally that the new pattern matches the preload-eligible
value and rejects three degraded forms (short max-age, missing
includeSubDomains, missing preload). Addresses @sara's round-2 note
on PR #499 — "presence check, not value check".
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
8fcf653cb0