Add subdomain-takeover fingerprints for more services

[sanmaxdev]

SentinelDeck flags dangling subdomains vulnerable to takeover by matching service fingerprints in src/sentineldeck/scanners/takeover.py (the SERVICES list). Expanding coverage is a perfect first contribution.

What to do

1. Pick one or more services not already covered, using https://github.com/EdOverflow/can-i-take-over-xyz (e.g. Shopify, Fastly, Ghost, Surge.sh, Tumblr, Webflow, Help Scout).
2. Add an entry to SERVICES with the CNAME pattern(s) and the response fingerprint string that indicates an unclaimed resource.
3. Add or extend a case in tests/test_takeover.py.

Acceptance

• New service entry + a test that proves it matches.
• ruff check . and pytest -q pass.
• Stays passive: detection is fingerprint-matching only, no claiming or exploitation.

Comment to claim it and ask any questions.