Extract conversion logic to hijri-core. All Hijri algorithms now
live in that package and are re-exported with identical signatures.
Fix weekday, era, and time token bugs. Dual CJS/ESM build. Full
test suite. CI and wiki workflows. Zero breaking API changes.
All Hijri conversion logic (UAQ table, FCNA algorithm, month/weekday
names, isValidHijriDate) now lives in hijri-core and is re-exported
from this package with identical signatures. Zero breaking changes:
the public API surface, type exports, and behavior are unchanged.
src/fcna.ts removed — FCNA engine is in hijri-core.
src/hDates.ts, hMonths.ts, hWeekdays.ts, utils.ts, toHijri.ts,
toGregorian.ts all rewritten as thin re-exports or single-line wrappers.
hijri-core added as a runtime dependency.
