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/calendar/saints/our-lady-of-the-snows.yml

@@ -0,0 +1,31 @@
+# Read directly from the reference engine (`../divinum-officium-reference`,
+# per memory vu-reference-engine-file-layout, not a live query): untagged/
+# default [Rank] block of `web/www/horas/Latin/Sancti/08-05.txt` --
+# "Sanctæ Mariæ Virginis ad Nives;;Duplex majus;;4;;ex C11". Previously
+# excluded from this app's calendar entirely under a stale "fixed BVM
+# feasts aren't modeled" note in sanctoral-calendar.yml's own August
+# comment -- wrong: this app already models three other fixed BVM feasts
+# the same way (assumption, immaculate-conception, nativity-bvm), and
+# this one has real, complete content too (Matins readings, sourced
+# directly; collect/antiphon via the Common-of-the-BVM fallback her own
+# `[Rule]` already points to, `ex C11` -- see collect-c11.yml and
+# benedictus-antiphon-common-of-the-bvm.yml). No `propers` of her own:
+# unlike the other three BVM feasts (each of which has real unique
+# collect/antiphon text), her file has none, so `collectCommon`/
+# `benedictusCommon` is the correct mechanism here, same as any other
+# `propers: null` saint falling back to a shared Common.
+id: our-lady-of-the-snows
+name: "Our Lady of the Snows (Dedication of St. Mary Major)"
+rank: duplex-majus
+common: common-of-the-bvm
+propers: null
+collectCommon: collect-c11
+# collect-c11's own text has no {N} placeholder to substitute (it
+# addresses "fámulis tuis" generically, not the saint by name) --
+# collectName is still required by getDayCollect's own lookup, but its
+# value is never actually used for this particular Common.
+collectName:
+  la: []
+  en: []
+minorHoursCommon: common-of-the-bvm
+benedictusCommon: common-of-the-bvm