calendar: pull January's sanctoral calendar (pre-1955 pull, 1/12)

20 saints for January, verified per-day against Divinum Officium (Monastic
Tridentinum 1617): 13 that actually win their day outright (rank pulled
from a live per-date query, since the static 1570/M1617 calendar text
files turned out unreliable once monastic-specific overrides apply) and
7 stubs for saints that only ever get commemorated, with an explicitly
flagged, unverified simplex rank guess pending correction.

Deliberately out of scope: pure octave-continuation days (In Octava S.
Stephani, the Epiphany-octave ferias) and fixed-date feasts of the
Lord/BMV (Circumcision, Epiphany) — sanctoral only, not temporal.

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

src/data/calendar/saints/st-hilary-of-poitiers.yml

@@ -0,0 +1,11 @@
+# Verified against Divinum Officium (Monastic Tridentinum 1617), live kalendar
+# check (2029-01-23, no Sunday collision) -- winner outright, Semiduplex. Own
+# proper collect, no unique antiphon of his own. (Picked 2029 deliberately --
+# 2027's Jan 23 turned out to already be governed by that week's temporal day
+# instead, a reminder that a fixed fest's *rank* is year-independent but
+# whether it actually wins isn't.)
+id: st-hilary-of-poitiers
+name: "St. Hilary of Poitiers, Bishop, Confessor and Doctor of the Church"
+rank: semiduplex
+common: common-of-a-confessor-bishop
+propers: "st-hilary-of-poitiers"