Author 10 sanctoral Common-category Magnificat antiphons

getMagnificatAntiphon's Common-category fallback
(magnificat-antiphon-${benedictusCommon}) had never been authored for
any of the 11 real Common categories saints fall back to -- only the
temporal-cycle side of this gap had been closed previously. Sourced
each from its Commune file's own [Ant 3] (Second Vespers), live-verified
against Ss. Placid and Companions, St. Blaise, and St. John Gualbert's
real evenings.

common-of-a-vigil (the 11th category) is handled separately, in code --
see the next commit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014QEe9oTbn1UjQVAYcCoW1a

src/data/propers/common/magnificat-antiphon-common-of-several-martyrs.yml

@@ -0,0 +1,17 @@
+# Second Vespers Magnificat antiphon for `common-of-several-martyrs`
+# (Commune Plurimorum Martyrum, Latin/Commune/C3.txt's own [Ant 3] --
+# confirmed by file position and live-verified directly: Ss. Placid and
+# Companions' own Second Vespers (10-05-2026, no "Vespera de sequenti")
+# renders this exact text, while the evening before (10-04-2026, "Vespera
+# de sequenti") renders C3's own [Ant 1] instead -- pins down Ant1 =
+# First Vespers, Ant3 = Second Vespers for this file layout. Ant 2 in
+# the same file matches the already-authored
+# benedictus-antiphon-common-of-several-martyrs.yml's "Vestri capilli
+# capitis" text exactly.
+id: magnificat-antiphon-common-of-several-martyrs
+text:
+  la: "Gaudent in cælis * ánimæ Sanctórum, qui Christi vestígia sunt secúti: et quia pro ejus amóre sánguinem suum fudérunt, ídeo cum Christo exsúltant sine fine."
+  en: "In heaven do rejoice the souls of the Saints * who have followed the steps of Christ; and because they shed their blood for the love of Christ, therefore shall they be made glad for ever with Christ."
+status:
+  la: verified
+  en: verified