chore: update website Hugo signer pin

[jt55401]

Summary

• update the Hugo module to d656523d13f7ee90a4f810d91bd575829060ce41
• refresh README, CI, go.mod, and go.sum pins
• render contact addresses as text so signed sections satisfy the HTTPS-only URL profile

Verification

• npm ci --ignore-scripts
• hugo --minify
• npx pagefind --site public
• npm run build
• signer dry-run across all eight signed pages
• GitHub Build Site and Sign content checks