Function buildLatencyPath

buildLatencyPath(channel: ChannelId, steps: readonly LatencyStep[]): LatencyPath
Sum a path's steps into a LatencyPath. Centralises the totalling so the engine and tests agree on the arithmetic.
Parameters
- channel: ChannelId
  the path's input channel
- steps: readonly LatencyStep[]
  the per-element latency steps in audio order
Returns LatencyPath
the path with totalMs = Σ steps[].latencyMs and effectHops = the count of plugin (mod-host effect_N) steps