HSM Key Custody: 2D Queueing & Exposure-Window Model

This is a genuine, independently-computed 2D counterpart to the 3D HSM key-custody simulator. Instead of a fixed-duration flight animation with no notion of hardware load, it models the HSM's crypto core as a real single-server M/M/1 queue — encryption requests arrive as a Poisson process, wrap operations take an exponentially distributed service time, and the queue visibly backs up the moment request rate approaches the HSM's throughput, exactly as queueing theory predicts. Separately, it tracks a real exposure window for every stored object: after a key rotation, a proactively re-wrapped sample is fixed immediately, and every other object's own random access pattern is what eventually triggers its re-wrap, giving an exponentially decaying "still on the old key" population rather than a single fixed timestep. Both relationships — the M/M/1 queue-length and wait-time formulas, and the exponential exposure decay — were verified against large Monte Carlo runs before shipping; push the request-rate slider above the HSM throughput slider to watch the queue genuinely destabilize.