Every date function returns null rather than inferring a missing year,
month or end date. A source that does not state an end yields
endsAt: null, never a plausible guess — a confidently wrong end date is
the failure this product exists to prevent.
Handles the three formats seen on Game8: "August 12, 2026",
"August 12 - September 21, 2026" (year applies to both ends, rolling the
start back when the range crosses New Year), and a slash datetime range.
Abbreviated months parse too, so a source switching to "Apr. 29" does not
silently drop events.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
