feat(of): seasonal weekday ferials from catholic-resources.org + date-based late Advent

Re-sources the proper weekdays of Advent (weeks 1-3), Lent, and Eastertide from
catholic-resources.org (scripts/genlect-of-season-ferials-cr.py; single-cycle, so
both -I/-II keys get the same readings). The diff caught real niedziela defects:
- Easter weekday first readings contaminated (easter-3-mon had 1 Cor 15 instead
  of Acts 6:8-15; easter-4-thu had Rev 12 instead of Acts 13:13-25).
- The Easter octave weekdays (Easter Mon-Sat) had no readings at all.
- Stray psalm-numbering artifacts (147A(146), Ps42(41)) cleared.

Late Advent (Dec 17-24) is proper to the DATE, not the Advent week, so temporal.go
now keys those days 'advent-dec-<day>' (fixing the same by-date/by-week collision
as the OT numbering) and the generator supplies them (Dec 17 = the genealogy
Matt 1:1-17; Dec 24 = the Benedictus).

157 seasonal ferial-days render across 2026-2028 with 1 residual gap
(christmas-octave-fri). Adds TestOFSeasonalFerials, credits the source, bumps to
0.43.0. Christmas-season weekdays (Dec 29-31, Jan 2-5) remain niedziela-sourced
(CR's shifted layout + Epiphany-dependent assignment -- a documented follow-up).

1 files changed, 5 insertions, 0 deletions

diff --git a/internal/calendar/temporal.go b/internal/calendar/temporal.go
index ab1a742..dadae49 100644
--- a/internal/calendar/temporal.go
+++ b/internal/calendar/temporal.go
@@ -215,6 +215,11 @@ func temporal(date time.Time, sel Selection) temporalDay {
 		if sun {
 			return sundayDay(Advent, "advent-sunday-"+itoa(week), col, week)
 		}
+		// From Dec 17 the weekday readings are proper to the DATE (the "O Antiphons"
+		// days), not the Advent week, so key them by date rather than by week-day.
+		if privFeria && date.Day() <= 24 {
+			return ferialDay(Advent, "advent-dec-"+itoa(date.Day()), Violet, week, true)
+		}
 		return ferialDay(Advent, "advent-"+itoa(week)+"-"+weekdayAbbr(wd), Violet, week, privFeria)
 
 	case !date.Before(christmasThis): // Dec 25..Dec 31 — Christmas octave