feat(of): Christmas-season weekday ferials from catholic-resources.org (date-based)

Completes the seasonal weekday lectionary. The Christmas-season weekdays sit on
the AdventChristmas page in a SHIFTED 6-column layout (Day in c[1], not c[2] like
Advent's 7-column) -- the generator now finds the Day column wherever it is. Adds
date-based slugs to temporal.go: christmas-dec-<29..31> (octave), christmas-jan-<2..7>
(before Epiphany), christmas-after-epiphany-<weekday> (before the Baptism). Fixes
the christmas-octave-fri coverage gap and the by-date/by-week collision.

362/362 seasonal ferial-days render across 2026-2029 with 0 gaps. Extends
TestOFSeasonalFerials. All of Advent/Lent/Easter/Christmas weekdays now CR-sourced;
only the Commons remain (optional -- memorials default to the ferial).

3 files changed, 164 insertions, 1 deletions

diff --git a/internal/caldata/of-lectionary.ini b/internal/caldata/of-lectionary.ini
index 8d36425..41b68cb 100644
--- a/internal/caldata/of-lectionary.ini
+++ b/internal/caldata/of-lectionary.ini
@@ -5000,3 +5000,153 @@ gospel = John 16:16-20
 first = The Acts 18:1-8
 psalm = Psalms 98:1,2-3ab,3cd-4
 gospel = John 16:16-20
+
+[christmas-dec-29-I]
+first = 1 John 2:3-11
+psalm = Psalms 96:1-2a,2b-3,5b-6
+gospel = Luke 2:22-35
+
+[christmas-dec-29-II]
+first = 1 John 2:3-11
+psalm = Psalms 96:1-2a,2b-3,5b-6
+gospel = Luke 2:22-35
+
+[christmas-dec-30-I]
+first = 1 John 2:12-17
+psalm = Psalms 96:7-8a,8b-9,10
+gospel = Luke 2:36-40
+
+[christmas-dec-30-II]
+first = 1 John 2:12-17
+psalm = Psalms 96:7-8a,8b-9,10
+gospel = Luke 2:36-40
+
+[christmas-dec-31-I]
+first = 1 John 2:18-21
+psalm = Psalms 96:1-2,11-12,13
+gospel = John 1:1-18
+
+[christmas-dec-31-II]
+first = 1 John 2:18-21
+psalm = Psalms 96:1-2,11-12,13
+gospel = John 1:1-18
+
+[christmas-jan-2-I]
+first = 1 John 2:22-28
+psalm = Psalms 98:1,2-3ab,3cd-4
+gospel = John 1:19-28
+
+[christmas-jan-2-II]
+first = 1 John 2:22-28
+psalm = Psalms 98:1,2-3ab,3cd-4
+gospel = John 1:19-28
+
+[christmas-jan-3-I]
+first = 1 John 2:29-3:6
+psalm = Psalms 98:1,3cd-4,5-6
+gospel = John 1:29-34
+
+[christmas-jan-3-II]
+first = 1 John 2:29-3:6
+psalm = Psalms 98:1,3cd-4,5-6
+gospel = John 1:29-34
+
+[christmas-jan-4-I]
+first = 1 John 3:7-10
+psalm = Psalms 98:1,7-8,9
+gospel = John 1:35-42
+
+[christmas-jan-4-II]
+first = 1 John 3:7-10
+psalm = Psalms 98:1,7-8,9
+gospel = John 1:35-42
+
+[christmas-jan-5-I]
+first = 1 John 3:11-21
+psalm = Psalms 100:1b-2,3,4,5
+gospel = John 1:43-51
+
+[christmas-jan-5-II]
+first = 1 John 3:11-21
+psalm = Psalms 100:1b-2,3,4,5
+gospel = John 1:43-51
+
+[christmas-jan-6-I]
+first = 1 John 5:5-13
+psalm = Psalms 147:12-13,14-15,19-20
+gospel = Mark 1:7-11
+
+[christmas-jan-6-II]
+first = 1 John 5:5-13
+psalm = Psalms 147:12-13,14-15,19-20
+gospel = Mark 1:7-11
+
+[christmas-jan-7-I]
+first = 1 John 5:14-21
+psalm = Psalms 149:1-2,3-4,5+6a+9b
+gospel = John 2:1-11
+
+[christmas-jan-7-II]
+first = 1 John 5:14-21
+psalm = Psalms 149:1-2,3-4,5+6a+9b
+gospel = John 2:1-11
+
+[christmas-after-epiphany-mon-I]
+first = 1 John 3:22-4:6
+psalm = Psalms 2:7bc-8,10-12a
+gospel = Matthew 4:12-17,23-25
+
+[christmas-after-epiphany-mon-II]
+first = 1 John 3:22-4:6
+psalm = Psalms 2:7bc-8,10-12a
+gospel = Matthew 4:12-17,23-25
+
+[christmas-after-epiphany-tue-I]
+first = 1 John 4:7-10
+psalm = Psalms 72:1-2,3-4,7-8
+gospel = Mark 6:34-44
+
+[christmas-after-epiphany-tue-II]
+first = 1 John 4:7-10
+psalm = Psalms 72:1-2,3-4,7-8
+gospel = Mark 6:34-44
+
+[christmas-after-epiphany-wed-I]
+first = 1 John 4:11-18
+psalm = Psalms 72:1-2,10,12-13
+gospel = Mark 6:45-52
+
+[christmas-after-epiphany-wed-II]
+first = 1 John 4:11-18
+psalm = Psalms 72:1-2,10,12-13
+gospel = Mark 6:45-52
+
+[christmas-after-epiphany-thu-I]
+first = 1 John 4:19-5:4
+psalm = Psalms 72:1-2,14+15bc,17
+gospel = Luke 4:14-22a
+
+[christmas-after-epiphany-thu-II]
+first = 1 John 4:19-5:4
+psalm = Psalms 72:1-2,14+15bc,17
+gospel = Luke 4:14-22a
+
+[christmas-after-epiphany-fri-I]
+first = 1 John 5:5-13
+psalm = Psalms 147:12-13,14-15,19-20
+gospel = Luke 5:12-16
+
+[christmas-after-epiphany-fri-II]
+first = 1 John 5:5-13
+psalm = Psalms 147:12-13,14-15,19-20
+gospel = Luke 5:12-16
+
+[christmas-after-epiphany-sat-I]
+first = 1 John 5:14-21
+psalm = Psalms 149:1-2,3-4,5+6a+9b
+gospel = John 3:22-30
+
+[christmas-after-epiphany-sat-II]
+first = 1 John 5:14-21
+psalm = Psalms 149:1-2,3-4,5+6a+9b
+gospel = John 3:22-30
diff --git a/internal/caldata/of_test.go b/internal/caldata/of_test.go
index 086883a..ca5cc24 100644
--- a/internal/caldata/of_test.go
+++ b/internal/caldata/of_test.go
@@ -95,6 +95,9 @@ func TestOFSeasonalFerials(t *testing.T) {
 		{"easter-octave-mon-I", "Acts 2:14"}, // was absent
 		{"advent-dec-17-I", "Genesis 49"},
 		{"advent-dec-24-I", "2 Samuel 7"},
+		{"christmas-dec-29-I", "1 John 2:3-11"},           // Christmas octave, by date
+		{"christmas-jan-2-I", "1 John 2:22-28"},           // before Epiphany, by date
+		{"christmas-after-epiphany-mon-I", "1 John 3:22"}, // after Epiphany, by weekday
 	} {
 		var first string
 		for _, r := range TemporalReadings("new", tc.key) {
diff --git a/internal/calendar/temporal.go b/internal/calendar/temporal.go
index dadae49..b0dc653 100644
--- a/internal/calendar/temporal.go
+++ b/internal/calendar/temporal.go
@@ -223,13 +223,23 @@ func temporal(date time.Time, sel Selection) temporalDay {
 		return ferialDay(Advent, "advent-"+itoa(week)+"-"+weekdayAbbr(wd), Violet, week, privFeria)
 
 	case !date.Before(christmasThis): // Dec 25..Dec 31 — Christmas octave
+		// The octave-day ferials (Dec 29-31) have readings proper to the date;
+		// Dec 25-28 are the Nativity and its feasts (Stephen/John/Innocents).
+		if date.Day() >= 29 {
+			return ferialDay(Christmas, "christmas-dec-"+itoa(date.Day()), White, 0, false)
+		}
 		return ferialDay(Christmas, "christmas-octave-"+weekdayAbbr(wd), White, 0, false)
 
 	case !date.After(baptismThis): // Jan 1..Baptism — Christmas season
 		if sun {
 			return sundayDay(Christmas, "christmas-sunday-"+weekdayAbbr(wd), White, 0)
 		}
-		return ferialDay(Christmas, "christmas-"+weekdayAbbr(wd), White, 0, false)
+		// Before Epiphany the weekdays are proper to the date (Jan 2-7); after
+		// Epiphany they are keyed by weekday (the days before the Baptism).
+		if date.Before(epiphany(y, sel)) {
+			return ferialDay(Christmas, "christmas-jan-"+itoa(date.Day()), White, 0, false)
+		}
+		return ferialDay(Christmas, "christmas-after-epiphany-"+weekdayAbbr(wd), White, 0, false)
 
 	default: // Ordinary Time (span 1: after Baptism..before Lent; span 2: after Pentecost..before Advent)
 		var week int