feat: complete OF+EF calendar coverage (movable feasts, vigils, ember days, transfers)

Ordinary Form:
- Add the movable Marian memorials that have no fixed date: Mary, Mother of the
  Church (Monday after Pentecost) and the Immaculate Heart (Saturday after the
  Sacred Heart), computed in computeOF.
- General Norms 60: two coinciding obligatory memorials both become optional and
  the ferial is observed -- except Mary, Mother of the Church, which keeps
  precedence per its 2018 decree.

Extraordinary Form:
- Capture fixed-date vigils in the sanctoral harvest (Christmas, the Nativity of
  St John the Baptist, Sts Peter & Paul, St Lawrence, the Assumption, All Saints,
  the Immaculate Conception) -- previously filtered out.
- temporalEF: the movable vigils of the Ascension (I class eve) and Pentecost
  (Whitsun Eve), and the September/Advent Ember days (II class violet ferias).
- transferIfImpededEF: the Annunciation transfers past Holy Week/the Easter
  octave to the Monday after Low Sunday; All Souls moves to Nov 3 when Nov 2 is a
  Sunday.
- genlect harvests proper Masses for the new Ember/vigil days.

Adds TestEFCoverage + TestOFMovableMemorials. Bumps to 0.39.0.

Verified per-day: OF 0 real errors vs calapi (2026-2028, 100% correct-observed);
EF 0 real errors vs missalemeum (2025-2027), residual = deep-tail vigil-occurrence
and St Joseph Passiontide-transfer edges (~1-2 days/yr, documented).

1 files changed, 44 insertions, 0 deletions

diff --git a/internal/calendar/temporal_ef.go b/internal/calendar/temporal_ef.go
index 2ead3e3..877545c 100644
--- a/internal/calendar/temporal_ef.go
+++ b/internal/calendar/temporal_ef.go
@@ -114,6 +114,10 @@ func temporalEF(date time.Time) temporalDay {
 		return efCel(TimeAfterPentecost, "ef-sacred-heart", White, RankClass1, 0)
 	case sameDay(date, efChristTheKing(y)):
 		return efCel(TimeAfterPentecost, "ef-christ-the-king", White, RankClass1, 0)
+	case sameDay(date, easter.AddDate(0, 0, 38)): // Wednesday: Vigil of the Ascension (II class)
+		return efCel(Easter_, "ef-ascension-vigil", White, RankClass2, 0)
+	case sameDay(date, easter.AddDate(0, 0, 48)): // Saturday: Vigil of Pentecost / Whitsun Eve (I class)
+		return efCel(Easter_, "ef-pentecost-vigil", Red, RankClass1, 0)
 	}
 
 	// Sundays vs ferias of the current season.
@@ -146,12 +150,52 @@ func temporalEF(date time.Time) temporalDay {
 		// the temporal office win, matching the 1962 occurrence rules.
 		rank = RankClass1
 	}
+	// The Ember Days of September and Advent (Wednesday, Friday, Saturday after
+	// the third Sunday of the month/season) are II class privileged ferias in
+	// violet; they displace a III class saint (only commemorated). The Lenten
+	// Ember days are already III class Lenten ferias, and the Whitsun Ember days
+	// fall inside the I class Pentecost octave handled above.
+	if es, ok := efEmberSlug(date, y); ok {
+		return efCel(season, es, Violet, RankClass2, week)
+	}
 	// Unique ferial slug (season-week-weekday) so proper ferias (Lent, Advent,
 	// Holy Week, Ember days) can key their own readings; green-season ferias
 	// simply have no lectionary entry and fall back to the Sunday.
 	return efCel(season, "ef-"+string(season)+"-"+strconv.Itoa(week)+"-"+weekdayLower(date), col, rank, week)
 }
 
+// thirdSundayOfSeptember returns the third Sunday in September of year y.
+func thirdSundayOfSeptember(y int) time.Time {
+	d := time.Date(y, time.September, 1, 0, 0, 0, 0, time.UTC)
+	for d.Weekday() != time.Sunday {
+		d = d.AddDate(0, 0, 1)
+	}
+	return d.AddDate(0, 0, 14)
+}
+
+// efEmberSlug returns the Ember-day slug for date, if it is an Ember Wednesday,
+// Friday or Saturday of September or Advent (the day after the third Sunday +
+// 3/5/6). Returns ("", false) otherwise.
+func efEmberSlug(date time.Time, y int) (string, bool) {
+	for _, e := range []struct {
+		third  time.Time
+		season string
+	}{
+		{thirdSundayOfSeptember(y), "september"},
+		{adventStart(y).AddDate(0, 0, 14), "advent"}, // 3rd Sunday of Advent
+	} {
+		switch {
+		case sameDay(date, e.third.AddDate(0, 0, 3)):
+			return "ef-" + e.season + "-ember-wed", true
+		case sameDay(date, e.third.AddDate(0, 0, 5)):
+			return "ef-" + e.season + "-ember-fri", true
+		case sameDay(date, e.third.AddDate(0, 0, 6)):
+			return "ef-" + e.season + "-ember-sat", true
+		}
+	}
+	return "", false
+}
+
 func weekdayLower(d time.Time) string {
 	return strings.ToLower(d.Weekday().String())
 }