Add May sanctoral content: 10 saints plus the Queenship of the BVM

Continues the full-year sanctoral import (see TODO.md/memory for Jan-Apr):
St. Pius V, St. Antoninus, St. Robert Bellarmine, St. John Baptist de la
Salle, St. Paschal Baylon, St. Venantius, St. Bernardine of Siena, St. John
Baptist de Rossi, St. Augustine of Canterbury, St. Mary Magdalene de Pazzi,
and the Queenship of the BVM (May 31, Duplex II Classis, instituted by Pius
XII's 1954 "Ad cæli Reginam" — full proper content, not a Common fallback).

Adding the Queenship to May 31 surfaces a real collision with Trinity
Sunday in years where Trinity falls on May 31 (2026): since this app
models Trinitytide Sundays as plain ordinary-sunday with no special
first-class standing, a Duplex+ sanctoral feast wins outright there per
the existing precedence rule. Updated the two tests pinned to that date
accordingly, with a third moved to a Trinity Sunday date (2023-06-04)
free of any sanctoral entry to keep testing the octave-vs-anchor-day
interaction in isolation.

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

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

@@ -0,0 +1,16 @@
+# Read directly from the reference engine: untagged/default [Rank]
+# block of `web/www/horas/Latin/Sancti/05-18.txt` -- "Duplex;;3;;vide
+# C2a" (Common of a Martyr). Own real proper [Oratio]. No [Ant 1] of
+# his own -- benedictusCommon/minorHoursCommon fall back to the plain
+# Common of a Martyr, matching st-fidelis-of-sigmaringen.yml. No
+# Lectio7-9 in his own file -- defers to the Common's own Nocturn 3,
+# not transcribed here. Own proper Matins hymns (Hymnus Vespera/
+# Matutinum/Laudes) exist in the source but aren't modeled -- this
+# app's hour builders don't carry per-saint hymn text.
+id: st-venantius
+name: "St. Venantius, Martyr"
+rank: duplex
+common: common-of-a-martyr
+propers: "st-venantius"
+benedictusCommon: common-of-a-martyr
+minorHoursCommon: common-of-a-martyr