calendar: pull February's sanctoral calendar (pre-1955 pull, 2/12)

13 saints for February (12 real + the Vigil of St. Matthias), all
verified winning outright on a clean per-annum date — no secondary/
commemorated stubs needed this month, unlike January.

Two new scope exclusions found this month, beyond the usual octave/
temporal-continuation and fixed Lord/BVM feast ones: the generic
"Sanctae Mariae Sabbato" Saturday votive (not a real saint) and Feb 29's
leap-year redirect of the Vigil of St. Matthias (a real but not-yet-
modeled leap-day date shift).

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

src/data/calendar/saints/chair-of-st-peter-at-antioch.yml

@@ -0,0 +1,10 @@
+# Verified against Divinum Officium (Monastic Tridentinum 1617), live kalendar
+# check (2029-02-22, no Sunday collision) -- winner outright, Duplex majus.
+# The second of the two Chair-of-Peter feasts (see chair-of-st-peter-at-
+# rome.yml, Jan 18) -- this is the antiphon's true home, and the collect is
+# identical text to Rome's, both intentionally duplicated rather than shared.
+id: chair-of-st-peter-at-antioch
+name: "The Chair of St. Peter at Antioch"
+rank: duplex-majus
+common: common-of-an-apostle
+propers: "chair-of-st-peter-at-antioch"