Model Trinity Sunday as a real feast, not just a cosmetic label

Trinity Sunday wasn't modeled at all: getDayLabel had a purely
cosmetic "Trinity Sunday" label overlay for the Sunday after
Pentecost, but resolveTemporalId just fell back to post-pentecost-01
(ordinary-sunday category), so any Duplex+ saint assigned that date
(e.g. the Queenship of the BVM, fixed May 31) won outright, real
Trinity Sunday content never appearing anywhere.

Added a real temporal-feasts/trinity-sunday.yml record (Easter+56,
Duplex II. classis, live-verified). Per direct instruction,
unconditional: true (same shape as christ-the-king.yml) -- a
principal Sunday shouldn't lose a same-rank fixed-date collision, and
the one real collision case (Queenship of the BVM) isn't
independently verifiable against Monastic 1617 at all (that calendar
doesn't carry the Queenship feast -- May 31 there is St. Petronilla
instead).

Authored the full office and registered trinity-sunday in
ALWAYS_OVERRIDE_TEMPORAL_IDS -- the same generic mechanism already
built for the Pentecost-cluster fix, no new code needed: collect,
Benedictus/Magnificat antiphons, Matins hymn ("Summæ Deus cleméntiæ"),
Lauds/Vespers chapter (shared, Rom 11:33) and hymn (shared, "O lux
beáta Trínitas", already the pre-Urban VIII text), each hour's own
distinct responsory/versicle -- all live-verified 2026-05-31.

Fixed 3 pre-existing tests written around the old cosmetic-label
behavior, two of which had never-verified guesses baked in as if
correct: day-label.test.ts's "names the anchor day itself" test and
its "outranks an active octave" test (was asserting "Duplex I Class",
a guess -- the real live-verified rank is Duplex II);
transfer.test.ts's St. Felix I test.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AGjUyhUZJaSjiniEmnLdak

src/data/propers/common/matins-hymn-trinity-sunday.yml

@@ -0,0 +1,67 @@
+# Trinity Sunday's own Matins hymn ("Summæ Deus cleméntiæ") — shares its
+# opening stanza with the plain ferial Saturday hymn
+# (matins-hymn-ferial-saturday.yml's "Summæ Deus cleméntiæ, Mundíque
+# Factor máchinæ..."), but diverges completely from its second stanza
+# onward and is shorter overall (2 body stanzas + its own doxology,
+# not 4 + the shared weekday doxology) — a genuinely different hymn, not
+# a mislabeled duplicate. Live-verified against Divinum Officium
+# (Monastic Tridentinum 1617), Matins live query, 2026-05-31 (Trinity
+# Sunday itself). Self-contained — its own final stanza is a fixed,
+# unique doxology, not the shared weekday one.
+id: matins-hymn-trinity-sunday
+text:
+  la: >-
+    Summæ Deus cleméntiæ,
+
+    Mundíque Factor máchinæ,
+
+    Unus potentiáliter,
+
+    Trinúsque personáliter.
+
+
+    Da déxteram surgéntibus,
+
+    Exsúrgat ut mens sóbria,
+
+    Flagrans et in laudem Dei,
+
+    Grates repéndet débitas.
+
+
+    Glória Patri Dómino,
+
+    Glória Unigénito,
+
+    Una cum Sancto Spíritu,
+
+    In sempitérna sǽcula. Amen.
+  en: >-
+    O God, by whose command is swayed
+
+    This ordered world which thou hast made;
+
+    Parent of heavenly clemency,
+
+    In nature One, in persons Three;
+
+
+    Assist us while our minds we raise,
+
+    Inflamed with thy immortal praise;
+
+    That with our sober thoughts, we may
+
+    Forever our thanksgiving pay.
+
+
+    May age by age thy wonders tell,
+
+    Eternal praise thy works reveal,
+
+    And sing with the celestial host
+
+    The Father, Son, and Holy Ghost. Amen.
+status:
+  la: verified
+  en: verified