Add the O Antiphons (Dec 17-23) as an unconditional Vespers Magnificat override

advent-4's own remaining Magnificat-antiphon gap turned out to be a
mechanism problem, not missing content: Dec 17-23 always carries one of
the seven "O Antiphons" at Vespers, keyed to the calendar date itself,
not to whichever Advent week (advent-3 or advent-4, varies by year)
happens to govern that date -- a single per-week file was structurally
the wrong shape.

Added vespers-o-antiphons.yml (MM-DD keyed) and a new lookup tier in
getMagnificatAntiphon, checked unconditionally ahead of both the
per-week temporal file and a real sanctoral winner's own antiphon --
direct instruction: the O Antiphon wins this one text slot on these
seven dates regardless of who otherwise wins the day (e.g. St. Thomas,
Dec 21, still keeps every other part of his own office). Two of the
seven (O Clavis David/O Oriens, Dec 20-21) couldn't be live-verified --
every reference-engine track routes those two dates through St.
Thomas's Vigil/feast instead, which this app's own vigil-of-st-thomas.yml
already documents diverging from -- so they're marked draft rather than
verified.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ME8QNPdEmHSbSx1r6VmDRG

src/data/hours/vespers-o-antiphons.yml

@@ -0,0 +1,86 @@
+# The seven "O Antiphons" (Dec 17-23): the classic pre-Christmas Vespers
+# Magnificat antiphons, keyed by calendar date (`MM-DD`) rather than by
+# any Advent-week temporal id -- unlike every other week's proper
+# Magnificat antiphon (data/propers/temporal/advent-N-magnificat-
+# antiphon.yml, one file per Advent week), these seven don't belong to a
+# single Advent week at all, since Dec 17-23 can fall within either
+# Advent's 3rd or 4th week depending on the year (Advent's own governing
+# Sunday moves, see calendar/temporal-id.ts).
+#
+# See hours/resolve-common.ts's getMagnificatAntiphon for the date-keyed
+# lookup this feeds -- checked *unconditionally*, ahead of both the
+# per-week temporal file and a real sanctoral winner's own antiphon.
+# Direct user instruction (2026-08-30): the O Antiphon always wins this
+# one specific text slot on these seven dates, full stop, regardless of
+# who otherwise wins the day -- e.g. St. Thomas, Duplex II. classis,
+# Dec 21, still wins everything else about that day (chapter, hymn,
+# collect, Lauds' own Benedictus antiphon), just not the Magnificat
+# antiphon. This is a deliberate app-level design choice, not a
+# reconstruction of the reference engine's own behavior (its live query
+# shows Thomas's own antiphon on Dec 20/21 instead, see below) -- and it
+# means a saint's own real Magnificat antiphon, once authored, is
+# permanently unreachable at Vespers on whichever of these seven dates
+# that saint happens to occupy, under *this* calendar's own construction.
+# Kept on file anyway (worth having for a future differently-constructed,
+# e.g. user-editable, calendar) rather than treated as pointless to
+# author.
+#
+# 12-17/18/19/22/23 live-verified against Divinum Officium (Monastic
+# Tridentinum 1617), Vespers live query, 2027-12-17/18/19/22/23 --
+# genuinely clean dates in this app's own calendar (no sanctoral entry on
+# any of the five, confirmed against data/calendar/sanctoral-calendar.yml).
+#
+# 12-20 ("O Clavis David") and 12-21 ("O Oriens") could NOT be
+# live-verified the same way: every version/track on the live engine
+# routes those two dates through St. Thomas's Vigil/feast (Dec 20/21)
+# instead of the plain ferial Proper of the Time, even in the plain
+# Tridentine 1570 track -- apparently a real modeling choice of that
+# engine (a Vigil of an Apostle actually displacing the ferial Magnificat
+# antiphon there), not an app-specific quirk. This app's own
+# vigil-of-st-thomas.yml already documents a deliberate divergence from
+# that engine on this exact date (the Vigil transfers away entirely here,
+# per the ordinary privileged-feria/vigil rule, rather than claiming
+# Second Vespers the way the live engine's Mass-only-commemoration
+# modeling implies) -- so the plain "O Clavis David"/"O Oriens" text
+# below, drawn from the standard, universally-fixed wording of these two
+# antiphons (unchanged across every edition of the Roman/Monastic
+# Breviary), is marked `draft` rather than `verified`: real, correctly
+# sourced liturgical text, just not confirmed against this app's own
+# primary live reference for lack of a clean query path.
+
+"12-17":
+  antiphon:
+    la: "O Sapiéntia, * quæ ex ore Altíssimi prodiísti, attíngens a fine usque ad finem, fórtiter suavitérque dispónens ómnia: veni ad docéndum nos viam prudéntiæ."
+    en: "O Wisdom, * that comest out of the mouth of the Most High, that reachest from one end to another, and dost mightily and sweetly order all things; come, to teach us the way of prudence!"
+
+"12-18":
+  antiphon:
+    la: "O Adonái, * et Dux domus Israël, qui Móysi in igne flammæ rubi apparuísti, et ei in Sina legem dedísti: veni ad rediméndum nos in brácchio exténto."
+    en: "O Adonai, * and Ruler of the house of Israel, who didst appear unto Moses in the burning bush, and gavest him the law in Sinai; come, to redeem us with an outstretched arm!"
+
+"12-19":
+  antiphon:
+    la: "O radix Jesse * qui stas in signum populórum, super quem continébunt reges os suum, quem gentes deprecabúntur: veni ad liberándum nos, jam noli tardáre."
+    en: "O Root of Jesse, * which standest for an ensign of the people, at whom the kings shall shut their mouths, to whom the Gentiles shall seek; come to deliver us, make no tarrying!"
+
+"12-20":
+  antiphon:
+    la: "O clavis David, * et sceptrum domus Israël; qui áperis, et nemo claudit; claudis, et nemo áperit: veni, et educ vinctum de domo cárceris, sedéntem in ténebris, et umbra mortis."
+    en: "O Key of David, * and Sceptre of the house of Israel, who openest and no man shutteth, who shuttest and no man openeth; come, and bring forth the prisoner from the prison-house, and him that sitteth in darkness and the shadow of death."
+  status: { la: draft, en: draft }
+
+"12-21":
+  antiphon:
+    la: "O Oriens, * splendor lucis ætérnæ, et sol justítiæ: veni, et illúmina sedéntes in ténebris, et umbra mortis."
+    en: "O Dayspring, * Brightness of light everlasting, and Sun of righteousness; come, and enlighten them that sit in darkness and the shadow of death."
+  status: { la: draft, en: draft }
+
+"12-22":
+  antiphon:
+    la: "O Rex géntium, * et desiderátus eárum, lapísque anguláris, qui facis útraque unum: veni, et salva hóminem, quem de limo formásti."
+    en: "O King of the Gentiles, * yea, and Desire thereof, O Cornerstone that makest of twain one; come to save man, whom thou hast made of the dust of the earth!"
+
+"12-23":
+  antiphon:
+    la: "O Emmánuel, * Rex et légifer noster, exspectátio géntium, et Salvátor eárum: veni ad salvándum nos, Dómine, Deus noster."
+    en: "O Emmanuel, our King * and our Law-giver, Longing of the Gentiles, yea, and Salvation thereof; come to save us, O Lord our God!"