Fix ordinary-Sunday precedence and unify getDayLabel's commemoration rendering

Two related fixes surfaced while chasing why St. Gregory Thaumaturgus
appeared to be misdated on Nov 18:

- calendar/commemorations.ts's `ordinary-sunday` case was transferring a
  Semiduplex (or lower) saint off the Sunday instead of commemorating it
  in place — an earlier, unverified guess. Live-verified against both
  Tridentine 1906 and Divino Afflatu 1954 (St. Gregory Thaumaturgus, St.
  Clement, St. Apollinaris, St. Thomas Becket, all real cases): the saint
  stays and is commemorated on the Sunday itself, same as Simplex, never
  pushed to the next open day. This is what was actually moving Gregory
  onto Nov 18 — not a data error. `applyChristmasOctaveSunday`'s own
  Dec 26-29 special case needed a matching adjustment (per its own
  documented intent, the displaced saint there is deliberately *not*
  commemorated in place, since he reappears in full on Dec 30 instead).

- getDayLabel had five branches, each hand-assembling its own
  filter/format logic for which commemorations to show — which is why
  the octave phrasing, the closing-day title, and a missing Sunday
  commemoration turned into three separate bugs earlier instead of one.
  Replaced with a single shared `collectCommemorations` used by every
  branch. This also exposed that the sanctoral-winner branch never
  showed any commemorated saint at all, and every other branch only
  showed the *first* one (`.find()`), silently dropping real collisions
  — both now show every commemorated saint, matching this app's own
  generous-commemoration design.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/calendar/commemorations.ts

@@ -159,14 +159,22 @@ export function decideOccurrence(
         // Duplex+ wins outright; the Sunday itself is commemorated in return.
         return { winner: sanctoralWinner(sanctoral), commemorations: [{ kind: 'temporal', id: temporalId }] };
       }
-      if (sanctoral.rank === 'simplex') {
-        // Too minor to warrant its own day, but a plain commemoration
-        // doesn't cheapen it the way it would a Semiduplex.
+      if (sanctoral.rank !== 'vigil') {
+        // Semiduplex or Simplex: commemorated, not transferred — live-
+        // verified (both Tridentine 1906 and Divino Afflatu 1954, the two
+        // calendar tracks this app blends): St. Gregory Thaumaturgus
+        // (Semiduplex) lands on the 6th Sunday after Epiphany, 2024-11-17,
+        // and is commemorated right there ("Commemoratio: S. Gregorii
+        // Thaumaturgi..."), not pushed to the next open day. Corrects an
+        // earlier, unverified guess that Semiduplex was "too important to
+        // merely commemorate" — Monastic Tridentinum 1617's own structural
+        // rubric *does* transfer him, but precedence here follows Divino
+        // Afflatu, not Monastic 1617's own (see CLAUDE.md).
         return { winner: temporalWinner, commemorations: [sanctoralCommemoration(sanctoral)] };
       }
-      // Semiduplex or Vigil: no room here at all, in either direction —
-      // better to preserve the feast whole on another day than downgrade
-      // it to a bare commemoration.
+      // A Vigil still transfers (backward, per transferDirectionOf) — a
+      // distinct rule from Semiduplex/Simplex above, not verified against
+      // this same live case and left as-is.
       return {
         winner: temporalWinner,
         commemorations: [],