Add Our Lady of the Snows (Aug 5) to the calendar

Previously excluded entirely under a stale "fixed BVM feasts aren't
modeled" note -- wrong: this app already models three other fixed BVM
feasts (assumption, immaculate-conception, nativity-bvm), and this one
has real, complete content too. Sancti/08-05.txt's untagged rank block
gives her Duplex Majus with real Nocturn 2/3 content (the
miraculous-snowfall founding legend of St. Mary Major); SanctiM/08-05.txt
confirms she's on the Monastic 1617 track too, reslicing the same
Lectio4-6.

Unlike the other three BVM feasts, she has no proper collect or
Benedictus antiphon of her own (her Rule says "ex C11" -- Common of
Feasts of the BVM) -- collect-c11.yml and
benedictus-antiphon-common-of-the-bvm.yml are real, reusable Common
templates, wired via collectCommon/benedictusCommon like any other
Common-only saint, not a private per-saint duplicate.

Live-checked via direct resolution: she wins outright on 2026-08-05 and
2027-08-05, with antiphon, collect, and Matins reading all resolving
verified. npm test (365 tests) and tsc --noEmit both pass.

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

src/data/propers/common/benedictus-antiphon-common-of-the-bvm.yml

@@ -0,0 +1,13 @@
+# Verified against the reference engine's own source data files:
+# web/www/horas/Latin/Commune/C11.txt's own [Ant 1] ("In Festis Beatae
+# Mariae Virginis" -- Common of Feasts of the BVM) and its English
+# counterpart. Reusable by any BVM feast keyed to `common: common-of-
+# the-bvm` (SaintRecord.benedictusCommon) that has no proper Benedictus
+# antiphon of its own -- e.g. our-lady-of-the-snows.yml.
+id: benedictus-antiphon-common-of-the-bvm
+text:
+  la: "Sancta María, * succúrre míseris, juva pusillánimes, réfove flébiles, ora pro pópulo, intérveni pro clero, intercéde pro devóto femíneo sexu: séntiant omnes tuum juvámen, quicúmque célebrant tuam sanctam festivitátem."
+  en: "O Holy Mary, * be thou an help to the helpless, a strength to the fearful, a comfort to the sorrowful; pray for the people, plead for the clergy, make intercession for all women vowed to God: may all that are keeping this thine holy Feast-day feel the might of thine assistance."
+status:
+  la: verified
+  en: verified