performance_analytics.find_horizon_date_range
*********************************************

spice.performance_analytics.find_horizon_date_range(as_of_date: datetime, horizon_str: str) -> tuple[datetime, datetime]

   Returns the start and end date for a given period relative to an
   as-of date.

   Parameters:
      * **as_of_date** -- The reference date to calculate ranges
        against. (YYYY-MM-DD format)

      * **horizon_str** -- A string specifying the desired period.
        Supported formats:

      * **periods** (*- Rolling*) -- "MTD"  → Month-to-date "QTD"  →
        Quarter-to-date "YTD"  → Year-to-date

      * **years** (*- Fiscal*) -- "2023", "2024", "2025"

      * **years** -- "FY2023", "FY2024", ...

      * **periods** -- "1M", "3M", "6M", "1Y", "2Y", ...

      * **Inception** (*- Since*) -- "SI"

   Returns:
      A tuple of (start_date, end_date) as datetime objects.

   Return type:
      tuple[datetime, datetime]
