propers: add May's collect and antiphon text

Real collect text for all 13 May saints that have one, plus a real
antiphon for the 3 that have one of their own (Ss. Philip and James, St.
John Before the Latin Gate, the Apparition of St. Michael) — same
extraction method as prior months. Two saints (St. Peter Celestine, St.
Urban I) have an [Ant 1] in the source that turned out to just be a
cross-reference to the generic Common template, not real unique text, so
no antiphon file was authored for them.

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

src/data/propers/common/apparition-of-st-michael-antiphon.yml

@@ -0,0 +1,11 @@
+# Verified against Divinum Officium (Latin/English Sancti/05-08.txt's own
+# [Ant 1] — the Lauds-hour antiphon, not Terce's, which falls back to a
+# generic Common text instead. See apparition-of-st-michael.yml on why
+# this is a separate record from st-michael.yml (Sept 29).
+id: apparition-of-st-michael-antiphon
+text:
+  la: "Dum sacrum mystérium * cérneret Joánnes, Archángelus Míchaël tuba cécinit: Ignósce, Dómine, Deus noster, qui áperis librum, et solvis signácula ejus, allelúja."
+  en: "While John was gazing * upon the holy mystery, the Archangel Michael sounded his trumpet: Forgive us, O Lord our God, Who openest the book, and loosest the seals thereof, alleluia."
+status:
+  la: verified
+  en: verified