Implements #109. Skills ship the chain-1 workflow (session file injection
through upload_progress filename + app LFI -> RCE, CVE-2026-109618/109619)
with hard gates: authorized targets only, program zero-day policy checked
before any live attempt (patches landed 2026-10-21 for 8.2-8.5), passive
detection before exploitation, lab-first practice via the vendored docker
lab, chains 2/3 (UAF, serializer mismatch) marked lab-only, one-shot
verification with a marker. Upstream PoCs vendored under scripts/poc/php2shell
with attribution and the MIT notice (upstream declares MIT in its README).
