calendar: pull October's sanctoral calendar (pre-1955 pull, 10/12)

16 saints (14 real winners + 2 stubs). Three monastic-calendar-specific
finds this month: Ss. Placid and Companions (Oct 5, St. Benedict's own
disciple, Duplex II. classis -- absent from the base Tridentine table
entirely), St. Justina (Oct 7, reassigns what the base table gives to
St. Marcus, Pope), and St. Gall (Oct 16, founder of St. Gallen, also
absent from the base table). No octave-gap exclusions this month.

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

src/data/calendar/saints/vigil-of-all-saints.yml

@@ -0,0 +1,8 @@
+# A real vigil (2025-10-31, clean year), distinct from the pre-existing
+# all-saints.yml (Nov 1). Own proper collect, generic enough that it
+# doesn't name any particular saint, no unique antiphon of its own.
+id: vigil-of-all-saints
+name: "Vigil of All Saints"
+rank: vigil
+common: common-of-a-vigil
+propers: "vigil-of-all-saints"