Add ServiceLatencyTracker with sorted-sample histogram, percentile getters (p50/p90/p99), average/min/max, reset, and immutable snapshot. Wire LatencyTracker and RecordServiceLatency onto Account. Cover with 11 xUnit tests.
Add ServiceLatencyTracker with sorted-sample histogram, percentile getters (p50/p90/p99), average/min/max, reset, and immutable snapshot. Wire LatencyTracker and RecordServiceLatency onto Account. Cover with 11 xUnit tests.