Moment.js plugin adding Hijri calendar support via hijri-core. Adds
toHijri(), fromHijri(), hijriYear/Month/Day(), isValidHijri(), and
formatHijri() to all Moment instances via fn prototype and module
augmentation. Format token escaping wraps substituted values in
moment bracket syntax [...] to prevent re-interpretation. UTC-midnight
date shift corrected by using getUTC* components + moment([y, m, d])
construction. 14 ESM + 8 CJS tests passing. Dual CJS/ESM build.
