Uses a fixed-window algorithm: each key tracks a window start time and a
count. When the current time reaches windowStart + windowMs, the window
resets. Amortised sweeps on increment reclaim expired windows, keeping
memory proportional to distinct keys in live windows plus the doubling-threshold
sweep slack (minimum threshold 1,024). Live windows are never evicted for a cap.
In-memory implementation of RateLimitStore.
Uses a fixed-window algorithm: each key tracks a window start time and a count. When the current time reaches windowStart + windowMs, the window resets. Amortised sweeps on increment reclaim expired windows, keeping memory proportional to distinct keys in live windows plus the doubling-threshold sweep slack (minimum threshold 1,024). Live windows are never evicted for a cap.