feat(ef): Rogation Monday and Tuesday (RG 87)

RG 87: "Litaniae minores seu Rogationes, per se, assignantur feriis II, III et
IV ante festum Ascensionis Domini." Easter+36 and +37 are that Monday and
Tuesday. RG 128(d) gives them violet -- "for the procession and Mass of the
Greater and Lesser Litanies" -- a penitential note inside white Paschaltide.
lectio computed no Rogation days at all and showed a plain paschaltide feria.

The WEDNESDAY is deliberately not built, and the test asserts its absence.
Easter+38 is by construction the Vigil of the Ascension, II class, which wins
the day outright; what the rubric asks for there is a COMMEMORATION, and this
function returns one office per day. colitur reaches it through a movable-date
entry in its sanctoral overlay. Extending the Rogation branch to +38 to
"complete" the rubric would silently displace the Vigil, so the test pins the
Vigil rather than leaving the omission to a comment.

Rank is left as the feria's: these are IV-class days and any III-class saint
displaces them, which is what makes the office rare. In 2026 all three are
impeded and none appears; 2027 has the Monday unimpeded, and lectio and
colitur are byte-identical across 2-5 May that year.

One oracle allow-list entry: missalemeum builds no Rogation days either and
shows a white feria, so it is the outlier here rather than lectio.

1 files changed, 20 insertions, 0 deletions

diff --git a/internal/calendar/oracle_ef_test.go b/internal/calendar/oracle_ef_test.go
index b765a34..79b31a5 100644
--- a/internal/calendar/oracle_ef_test.go
+++ b/internal/calendar/oracle_ef_test.go
@@ -128,6 +128,26 @@ type efAllow struct {
 
 var efAllowList = []efAllow{
 	{
+		// RG 87: "Litaniae minores seu Rogationes, per se, assignantur feriis
+		// II, III et IV ante festum Ascensionis Domini." The Monday and
+		// Tuesday before the Ascension are Rogation days, and RG 128(d) gives
+		// violet to "the procession and Mass of the Greater and Lesser
+		// Litanies" -- a penitential note inside white Paschaltide.
+		//
+		// missalemeum builds no Rogation days and shows a plain white
+		// paschaltide feria. It is the outlier here, not lectio: colitur has
+		// had these since its own v0.1 and the two engines now agree day for
+		// day. Rare in practice, because a III-class saint displaces them --
+		// in 2026 all three are impeded and none appears.
+		match: func(date string, day time.Time, o efOracleDay) bool {
+			e := calendar.Easter(day.Year())
+			off := int(day.Sub(e).Hours() / 24)
+			return off == 36 || off == 37
+		},
+		field:  "colour",
+		reason: "RG 87 + RG 128(d): the Rogation Monday and Tuesday before the Ascension are violet; missalemeum builds no Rogation days (colitur C8)",
+	},
+	{
 		// RG 124, "De coloribus paramentorum", section C "De colore rubro",
 		// both photographic scans word for word: 124(b) gives red to
 		// "Sanctorum Apostolorum et Evangelistarum, in eorum die natalicio,