Quantum Secret Sharing: 2D GHZ-State Parity Map

A dealer splits a secret bit across n parties by distributing one qubit each from an n-qubit GHZ state, encoding the bit as the eigenvalue of the collective X⊗X⊗...⊗X stabilizer. This 2D companion to the 3D GHZ secret-sharing simulator keeps the same real stabilizer-formalism physics — verified numerically to reproduce identical statistics — but renders it as a top-down, pannable and zoomable parity map: qubits fly from a central dealer node out to each party's station around a ring, and a dedicated running parity-history strip beneath the ring plots every round's measured product over time, a genuinely 2D-native diagnostic with no 3D equivalent. Occasional Z-basis "check" rounds double as a real disturbance test: toggle a dishonest party's intercept-resend attack on and watch both the correlation-check pass rate and the parity-history strip go noisy, exactly the signal a quantum secret-sharing protocol uses to catch a cheat.