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/hours/matins.ts

@@ -300,7 +300,13 @@ function ferialPsalmodyThreeNocturns(day: LiturgicalDay): [ResolvedPart[], Resol
  * user's own "be generous, not winner-takes-all" instruction (2026-08). */
 function nocturnReadingIds(day: LiturgicalDay, temporalId: string): string[] {
   const ids = new Set<string>();
-  if (day.winner.kind === 'sanctoral') ids.add(day.winner.id);
+  // Not gated to `kind === 'sanctoral'` -- a named temporal override (e.g.
+  // Immaculate Heart of Mary, calendar/index.ts's applyImmaculateHeart)
+  // has its own authored nocturn-readings file keyed by its own id too,
+  // distinct from the plain governing-Sunday `temporalId` added below.
+  // Harmless to include unconditionally: on an ordinary day `day.winner.id`
+  // already equals `temporalId`, so the Set just dedupes.
+  ids.add(day.winner.id);
   for (const c of day.commemorations) {
     if (c.kind === 'sanctoral') ids.add(c.id);
   }