Add 6 more April saints previously never added

St. Isidore of Seville, St. Vincent Ferrer, St. Hermenegild, St. Anselm,
St. Fidelis of Sigmaringen, St. Peter Canisius -- April complete.
St. Peter Canisius is the second common-of-a-confessor-doctor saint
(after St. John Damascene in March), same benedictusCommon reuse
pattern. St. Hugh, Abbot (Apr 1) checked and correctly skipped: his own
file is Commemoratio-rank with only a collect, no Lectio content at
all to source.

npm test (365 tests) and tsc --noEmit both pass.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/data/calendar/saints/st-anselm.yml

@@ -0,0 +1,18 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/04-21.txt` -- "vide C4a;;Duplex;;3;;".
+# No [Oratio]/[Ant 1] of its own in this file at all -- both fall back
+# to Common of a Confessor Bishop who is a Doctor (C4a), matching
+# st-ambrose.yml/st-isidore-of-seville.yml. Nocturn 3 (Lectio7-9) is a
+# direct `@Commune/C4a:LectioN in 2 loco` cross-reference, not
+# transcribed here.
+id: st-anselm
+name: "St. Anselm, Bishop, Confessor and Doctor of the Church"
+rank: duplex
+common: common-of-a-confessor-bishop
+propers: null
+collectCommon: collect-c4a
+collectName:
+  la: ["Ansélmum"]
+  en: ["Anselm"]
+minorHoursCommon: common-of-a-confessor-bishop
+benedictusCommon: common-of-a-confessor-bishop

src/data/calendar/saints/st-fidelis-of-sigmaringen.yml

@@ -0,0 +1,12 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/04-24.txt` -- "vide C2a;;Duplex;;3;;".
+# Own proper [Oratio]; no [Ant 1] of its own, so the Benedictus antiphon
+# falls back to Common of a Martyr (C2a), matching st-hermenegild.yml.
+# No Lectio7-9 in the source (6-lesson office).
+id: st-fidelis-of-sigmaringen
+name: "St. Fidelis of Sigmaringen, Martyr"
+rank: duplex
+common: common-of-a-martyr
+propers: "st-fidelis-of-sigmaringen"
+minorHoursCommon: common-of-a-martyr
+benedictusCommon: common-of-a-martyr

src/data/calendar/saints/st-hermenegild.yml

@@ -0,0 +1,13 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/04-13.txt` -- "vide C2a;;Semiduplex;;2.2;;".
+# Own proper [Oratio]; no [Ant 1] of its own, so the Benedictus antiphon
+# falls back to Common of a Martyr (C2a), matching st-christopher.yml.
+# Nocturn 3 (Lectio7-9) is a direct `@Commune/C2:LectioN` cross-reference,
+# not transcribed here.
+id: st-hermenegild
+name: "St. Hermenegild, Martyr"
+rank: semiduplex
+common: common-of-a-martyr
+propers: "st-hermenegild"
+minorHoursCommon: common-of-a-martyr
+benedictusCommon: common-of-a-martyr

src/data/calendar/saints/st-isidore-of-seville.yml

@@ -0,0 +1,16 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/04-04.txt` -- "vide C4a;;Duplex;;3;;".
+# No [Oratio]/[Ant 1] of its own in this file at all -- both fall back
+# to Common of a Confessor Bishop who is a Doctor (C4a), matching
+# st-ambrose.yml.
+id: st-isidore-of-seville
+name: "St. Isidore of Seville, Bishop, Confessor and Doctor of the Church"
+rank: duplex
+common: common-of-a-confessor-bishop
+propers: null
+collectCommon: collect-c4a
+collectName:
+  la: ["Isidórum"]
+  en: ["Isidore"]
+minorHoursCommon: common-of-a-confessor-bishop
+benedictusCommon: common-of-a-confessor-bishop

src/data/calendar/saints/st-peter-canisius.yml

@@ -0,0 +1,13 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/04-27.txt` -- "vide C5a;;Duplex;;3;;"
+# ("Commune Doctoris non Pontificis"). Own proper [Oratio] and Nocturn
+# 2-3 content. No [Ant 1] of its own; benedictusCommon points at the
+# already-authored `benedictus-antiphon-common-of-a-confessor-
+# bishop.yml` directly, same reasoning as st-john-damascene.yml (C5a's
+# own [Ant 1] is itself a cross-reference to C4a).
+id: st-peter-canisius
+name: "St. Peter Canisius, Confessor and Doctor of the Church"
+rank: duplex
+common: common-of-a-confessor-doctor
+propers: "st-peter-canisius"
+benedictusCommon: common-of-a-confessor-bishop

src/data/calendar/saints/st-vincent-ferrer.yml

@@ -0,0 +1,12 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/04-05.txt` -- "vide C5;;Duplex;;3;;".
+# Own proper [Oratio]; no [Ant 1] of its own, so the Benedictus antiphon
+# falls back to Common of a Confessor (C5), matching st-alexius.yml.
+# No Lectio7-9 in the source (6-lesson office).
+id: st-vincent-ferrer
+name: "St. Vincent Ferrer, Confessor"
+rank: duplex
+common: common-of-a-confessor
+propers: "st-vincent-ferrer"
+minorHoursCommon: common-of-a-confessor
+benedictusCommon: common-of-a-confessor

src/data/calendar/sanctoral-calendar.yml

@@ -90,12 +90,18 @@ days:
   # transfers due to Holy Week; that's the existing transfer machinery,
   # not something recorded specially here.
   "04-02": [st-francis-of-paola]
+  "04-04": [st-isidore-of-seville]
+  "04-05": [st-vincent-ferrer]
   "04-11": [st-leo-i]
+  "04-13": [st-hermenegild]
   "04-14": [ss-tiburtius-valerian-and-maximus]
   "04-17": [st-anicetus]
+  "04-21": [st-anselm]
   "04-22": [ss-soter-and-caius]
   "04-23": [st-george]
+  "04-24": [st-fidelis-of-sigmaringen]
   "04-25": [st-mark]
+  "04-27": [st-peter-canisius]
   "04-26": [ss-cletus-and-marcellinus]
   "04-28": [st-vitalis]
   "04-29": [st-robert, st-catherine-of-siena]