calendar: model octaves as a generic, data-driven mechanism

Adds calendar/octaves.ts: a lookback over the past week collecting every
octave (sanctoral or temporal) still active on a date, stacking multiple
at once (Christmas + St. Stephen + St. John + Holy Innocents all
commemorated together within the Christmas Octave). Declared via an
optional `octave` field on a saint's own record or a new small
TemporalFeastRecord (calendar/temporal-feasts.ts) for temporal ids like
Christmas/Pentecost that didn't have a metadata record before -- data-
driven per user design discussion, with `{ enabled: true }` alone using
sensible defaults (8 days, semiduplex threshold) so a minimal declaration
works without authored content.

Wired into resolveDay as a post-processing layer: doesn't change how a
single day's own precedence contest is decided, just adds commemorations
for active octaves and occasionally overrides the winner when the
occurring saint doesn't clear the strictest active octave's threshold.

Populated so far: St. Lawrence's own octave (the one that repeatedly cost
real saints their spot in August), the three Comites Christi octaves
(Stephen/John/Innocents -- Thomas of Canterbury deliberately excluded,
per discussion), and Pentecost's (duplex threshold, user-specified).
Pentecost's octave offsets are also removed from temporal-categories.yml's
privileged-feria-major classification, letting a real candidate reach the
new octave layer instead of being transferred away first -- with the
side effect that Pentecost's own Ember Saturday no longer forces a
transfer (a sub-threshold saint is now commemorated in place instead, see
tests/calendar/transfer.test.ts's updated case). Assumption, Nativity
BVM, Immaculate Conception, and All Saints' own octaves are not yet
populated with octave data -- deliberately deferred to a follow-up pass.

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

tests/calendar/december-sanctoral.test.ts

@@ -53,9 +53,11 @@ describe('December sanctoral pull (first pass, 12/12)', () => {
   });
 
   it('the Christmas Octave "Comites Christi" days each win outright with real propers, the Octave day commemorated in return', () => {
-    const stephen = resolveDay('2025-12-26');
-    const john = resolveDay('2025-12-27');
-    const innocents = resolveDay('2026-12-28');
+    // 2033 has no Sunday collision anywhere in Dec 26-31, so each of
+    // these resolves without a privileged-Sunday complication.
+    const stephen = resolveDay('2033-12-26');
+    const john = resolveDay('2033-12-27');
+    const innocents = resolveDay('2033-12-28');
     expect(stephen.winner).toEqual({
       kind: 'sanctoral',
       id: 'st-stephen-protomartyr',
@@ -75,21 +77,48 @@ describe('December sanctoral pull (first pass, 12/12)', () => {
       rank: 'duplex-2-classis',
     });
     for (const day of [stephen, john, innocents]) {
-      expect(day.commemorations.length).toBe(1);
-      expect(day.commemorations[0]?.kind).toBe('temporal');
       expect(getDayCollect(day).status.en).toBe('verified');
     }
+    // Each also carries the day's own Octave-of-the-Nativity commemoration
+    // plus Christmas's own octave, which keeps accumulating -- see the
+    // dedicated stacking test below for the full week's build-up.
+    expect(stephen.commemorations).toEqual([
+      { kind: 'temporal', id: expect.any(String) },
+      { kind: 'octave', id: 'christmas-day', name: 'Christmas' },
+    ]);
   });
 
   it('St. Thomas of Canterbury, only Semiduplex, still wins outright within the Christmas Octave -- the concrete case behind this month\'s temporal-category fix', () => {
-    const day = resolveDay('2025-12-29');
+    const day = resolveDay('2033-12-29');
     expect(day.winner).toEqual({
       kind: 'sanctoral',
       id: 'st-thomas-becket',
       name: 'St. Thomas of Canterbury, Bishop and Martyr',
       rank: 'semiduplex',
     });
-    expect(day.commemorations.length).toBe(1);
-    expect(day.commemorations[0]?.kind).toBe('temporal');
+    // Thomas himself has no octave (user-confirmed, 2026-08), but by his
+    // own day, Christmas + Stephen + John + Holy Innocents' octaves have
+    // all stacked up and commemorate alongside him.
+    expect(day.commemorations).toEqual([
+      { kind: 'temporal', id: expect.any(String) },
+      { kind: 'octave', id: 'christmas-day', name: 'Christmas' },
+      { kind: 'octave', id: 'st-stephen-protomartyr', name: 'St. Stephen, Protomartyr' },
+      { kind: 'octave', id: 'st-john-apostle', name: 'St. John, Apostle and Evangelist' },
+      { kind: 'octave', id: 'holy-innocents', name: 'The Holy Innocents, Martyrs' },
+    ]);
+  });
+
+  it('the Christmas Octave commemorations build up day by day as each Comites Christi feast starts its own octave', () => {
+    // Same clean year (2033) as above, walking the whole week to show the
+    // accumulation directly -- this is the concrete shape of "commemorations
+    // build up" the octave mechanism was built for.
+    const dec30 = resolveDay('2033-12-30'); // no saint of its own -- a plain Octave-of-the-Nativity day
+    expect(dec30.winner.kind).toBe('temporal');
+    expect(dec30.commemorations).toEqual([
+      { kind: 'octave', id: 'christmas-day', name: 'Christmas' },
+      { kind: 'octave', id: 'st-stephen-protomartyr', name: 'St. Stephen, Protomartyr' },
+      { kind: 'octave', id: 'st-john-apostle', name: 'St. John, Apostle and Evangelist' },
+      { kind: 'octave', id: 'holy-innocents', name: 'The Holy Innocents, Martyrs' },
+    ]);
   });
 });