propers: add December's collect and antiphon text

10 collects, 5 antiphons -- including backfilling the pre-existing
Immaculate Conception entry. St. Damasus's collect is Latin-only (no
English translation exists in the reference source at all); a few
others (All Saints, Bibiana, Immaculate Conception) needed their English
read directly from the raw source file after the live query's English
side either omitted the Oratio translation or rendered the wrong Marian
feast's text -- caught by cross-checking, not assumed.

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

src/data/propers/common/st-thomas-apostle-antiphon.yml

@@ -0,0 +1,9 @@
+# Verified against Divinum Officium (Latin/English Sancti/12-21.txt's own
+# [Ant 1] — the Lauds-hour antiphon, not Terce's.
+id: st-thomas-apostle-antiphon
+text:
+  la: "Quia vidísti me * Thoma, credidísti: beáti qui non vidérunt, et credidérunt, allelúja."
+  en: "Because thou hast seen me, * Thomas, thou hast believed: blessed are they that have not seen and have believed, alleluia."
+status:
+  la: verified
+  en: verified