Relocate Immaculate Heart of Mary off Aug 22 to Easter+69

Fixed Aug 22 collided outright with the Assumption's own octave-closing
day (both this project's blended calendar tracks are kept deliberately,
so one shouldn't permanently suppress the other). Moved IHM to the
Saturday after the Feast of the Sacred Heart -- its real diocesan date
from 1914 until Pius XII's 1944 fixed-date decree, and also the date the
1969 reform returned to.

Required real new mechanism, not just a data move: a new bespoke
calendar/index.ts override (applyImmaculateHeart, following the existing
applyMarianSaturday/applyChristTheKing precedent), a move from the
sanctoral saints store to the temporal-feasts store (different propers
lookup entirely), and a real bug fix in matins.ts's nocturnReadingIds,
which only ever picked up a *sanctoral* winner's own reading file.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VZSAgRi4QE4XRTqVto93zA

src/data/calendar/temporal-feasts/immaculate-heart-of-mary.yml

@@ -0,0 +1,14 @@
+# Relocated off the fixed Aug 22 date (2026-08-22 user decision) -- that
+# date collided outright with the Assumption's own octave-closing day,
+# which this project also deliberately keeps (see saints/assumption.yml).
+# Moved to the Saturday after the Feast of the Sacred Heart (Easter+69,
+# see calendar/index.ts's applyImmaculateHeart) -- the feast's own real
+# diocesan date from 1914 until Pius XII's 1944 fixed-date decree, and
+# also the date Paul VI's 1969 reform returned to, so it has continuity
+# on both sides of the Aug-22 interlude. Rank/name still sourced from
+# `web/www/horas/Latin/Sancti/08-22.txt`'s own [Rank] block, same as
+# before the move -- only the date assignment changed, not the office's
+# own content.
+id: immaculate-heart-of-mary
+name: "The Immaculate Heart of the Blessed Virgin Mary"
+rank: duplex-2-classis