Simulate a retry storm and stop it

A deterministic discrete-event simulation of 1,000 calls retrying against a provider that is down for 10 seconds and then takes 50 a second, with six policies (fixed, exponential, full jitter, equal jitter, full jitter with a 10% retry budget, and three stacked retry layers). Exponential backoff without jitter reproduces the lesson's 400 of 1,000 exactly, full jitter completes everything in about a minute, and the stacked layers send about eighteen attempts per call.