fiscal quarters

Resolve Indian FISCAL quarters deterministically — use this for any 'next N quarters', 'last N quarters', 'this/next/coming quarter', or 'quarters in FY__' request BEFORE filtering data. Indian FY = Apr–Mar; Q1 Apr–Jun, Q2 Jul–Sep, Q3 Oct–Dec, Q4 Jan–Mar (Q4 is next calendar year). `reference` is a YYYY-MM-DD anchor (defaults to today); `back`/`next` = how many quarters before/after the current on