CVE-2026-43981 Algernon: Race Condition in handle() shared LState

Algernon is a small self-contained pure-Go web server. Prior to 1.17.6, in engine/luahandler.go, the sync.RWMutex protecting LoadCommonFunctions is released before L.Push and L.PCall execute. Since gopher-lua's LState is explicitly not goroutine-safe, concurrent requests race on the shared state...