Add Matins hymn Common-of-Saints tier and a real invitatory-antiphon mechanism

resolveMatinsHymn gained a Common-category tier (override -> octave ->
Common category -> season -> ferial), reusing matins-psalmody-
overrides.ts's own getSaintRecord(id)?.common lookup pattern. The
invitatory antiphon (invitatoryParts), previously one hardcoded fixed
text for every day of the year with only full-vs-incipit doubling
varying by rank, now goes through a real resolveMatinsInvitatoryText
(override -> Common category -> season -> ferial, no octave tier) before
the doubling step.

Content authored this pass: Common-of-an-Apostle only, both hymn
(matins-hymn-common-of-an-apostle.yml, "Aeterna Christi munera") and
invitatory antiphon (matins-invitatory-common-of-an-apostle.yml, "Regem
Apostolorum Dominum"), both read directly from the reference engine's
Commune/C1.txt. Live-verified: St. Bartholomew (2026-08-24) and St.
Andrew (2026-11-30) both now resolve to this Common's text.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F25189JqjXddUhU9hM9nUS

src/data/propers/common/matins-invitatory-common-of-an-apostle.yml

@@ -0,0 +1,13 @@
+# The Common-of-an-Apostle's own invitatory antiphon ("Regem Apostolórum
+# Dóminum" / "The Lord, the King of Apostles"), read from the reference
+# engine's own Commune/C1.txt [Invit] line (both languages). Any winning
+# apostle with no proper invitatory antiphon of his own authored falls to
+# this Common tier (hours/matins.ts's resolveMatinsInvitatoryText) — e.g.
+# St. Bartholomew (2026-08-24, live-verified).
+id: matins-invitatory-common-of-an-apostle
+text:
+  la: "Regem Apostolórum Dóminum, * Veníte, adorémus."
+  en: "The Lord, the King of Apostles, * O come, let us adore."
+status:
+  la: verified
+  en: verified