Add Google Search Console verification TXT [skip release]

[johncarmack1984]

Summary

Adds the google-site-verification TXT for Google Search Console domain-property verification of stormdeck.live.

Route 53 allows only one TXT record-set per name, and the apex already holds the SPF policy (owned by StormdeckEmailStack). So the verification string is appended to that record's values rather than added as a second apex TXT (which Route 53 would reject). The construct's logical id stays Spf so CloudFormation updates the values in place instead of replacing the record.

Already applied to prod

StormdeckEmailStack is not CI-deployed (the deploy workflow deploys only StormdeckStack); it's a manual/local deploy like the OIDC stack. This change was deployed directly to the stormdeck account (us-east-2) — cdk diff showed only the apex TXT value addition, nothing else — and verified live:

$ dig +short TXT stormdeck.live
"google-site-verification=bEdN5MsLRKcHmi5xlGSQRal-T7iLtQnR9LKO9EkAvFQ"
"v=spf1 include:amazonses.com ~all"

This PR just brings the repo in sync with deployed reality. Note: merging will re-run the deploy workflow (idempotent StormdeckStack redeploy + feed prime); there's no rush since the record is already serving.

Docs & attribution

• N/A — infrastructure-only (a DNS verification record); no data source, behavior, cost, or attribution change.