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/ss-philip-and-james-antiphon.yml

@@ -0,0 +1,10 @@
+# Verified against Divinum Officium (Latin/English Sancti/05-01.txt's own
+# [Ant 1] — the Lauds-hour antiphon, not Terce's, which falls back to a
+# generic Common text instead.
+id: ss-philip-and-james-antiphon
+text:
+  la: "Non turbétur * cor vestrum, neque formídet: créditis in Deum, et in me crédite: in domo Patris mei mansiónes multæ sunt, allelúja, allelúja."
+  en: "Let not your heart be troubled, * neither let it be afraid: ye believe in God, believe also in me: in my Father's house are many mansions, alleluia, alleluia."
+status:
+  la: verified
+  en: verified