sundayOnOrBefore and firstSundayStrictlyAfter are calendar facts ("which
Sunday does this feria belong to"), not presentation logic — day-label.ts
was the only consumer so far, but a future temporal-propers content
resolver (PropersRef's still-unused source: 'temporal' branch) will need
the exact same arithmetic, just keyed for content ids instead of display
strings. Moving it now, while the shape is still small and well
understood, rather than duplicating it later.
day-label.ts keeps the actual display config (which anchor, "Trinity" vs
"Pentecost" wording) — that part stays presentation-only on purpose, since
it's also where a future counting-convention setting would hook in.
No behavior change: 88/88 tests still pass.
resolveDay() no longer hardcodes season: 'trinitytide'. Easter is
computed via the Anonymous Gregorian algorithm (verified against 16
known reference dates spanning 1583-2100); Advent/Christmastide/
Epiphanytide follow the Christmas-anchored rules (including Advent's
"Sunday nearest Nov 30"); Septuagesima through Trinitytide come from
easter-offsets.yml, reshaped from single named anchor points into real
ranges plus single-day overrides for Corpus Christi and Sacred Heart.
occurring feasts (calendar/feasts.ts) are still a stub — the sanctoral
calendar and Double-vs-not ranking are a separate, larger project.
will