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/chair-of-st-peter-at-rome.yml

@@ -0,0 +1,13 @@
+# Verified against Divinum Officium (Monastic Tridentinum 1617), live kalendar
+# check (2029-01-18, no Sunday collision) -- winner outright, Duplex majus.
+# About St. Peter the apostle's office, not a feast of the Lord -- kept in the
+# sanctoral store like the rest, distinct from the second Chair-of-Peter feast
+# at Antioch (Feb 22, not yet pulled). Own proper collect and antiphon --
+# the antiphon is a cross-reference in the source
+# (web/www/horas/Latin/Sancti/01-18.txt's [Ant 1] points at Sancti/02-22.txt,
+# since both Chair feasts share it).
+id: chair-of-st-peter-at-rome
+name: "The Chair of St. Peter at Rome"
+rank: duplex-majus
+common: common-of-an-apostle
+propers: "chair-of-st-peter-at-rome"