Benchmarks and intermittent demand

Toolset tsforecast_benchmarks: 2 tools.

Tool	What it does	Notes
`tsforecast_baselines`	Forecasts one series (y) or every series of a panel (data) with benchmark methods: naive (last value), seasonal naive, random walk with drift, historic average, window and seasonal window averages, the conformal seasonal pool (seasonal naive with sample-based intervals) and constant, zero or missing forecasts (fallbacks).
`tsforecast_intermittent`	Forecasts series with many zero periods (spare parts, slow-moving stock, rainfall, sporadic trades) with intermittent-demand methods: Croston classic, optimized and Syntetos-Boylan (SBA), ADIDA (temporal aggregation), IMAPA (multiple aggregation) and TSB (demand probability times size, handles obsolescence).

Inputs, limits and outputs are described in Fincept TS Forecast. Full schemas: fincept_describe_tool.