Add Ember-day mechanism (privileged feria, not a rank contest) + real content

Researched whether September/Advent Ember days belong in the
movable-feasts.ts table alongside Christ the King/Immaculate Heart of
Mary. Live-verified against the reference engine they don't: Ember days
are privileged ferias (a saint can still win outright against them), not
named feasts contesting the day by rank.

Two smaller pieces instead: calendar/temporal.ts's septemberEmberDayOffset
(Sunday nearest Sept 14, same "nearest" arithmetic adventStart already
used, factored into a shared nearestSunday helper) feeds a new
resolveTemporalCategory check giving those 3 dates privileged-feria-minor
(live-verified correct); calendar/ember-days.ts's applyEmberDay relabels
the day's own temporal id to the Ember day's own (so its real content is
found) when the feria itself wins, or adds a commemoration when a saint
does. Advent Ember days needed no precedence change -- Advent's own
season default already covers them.

Found and fixed a real bug along the way: matins.ts's nocturnReadingIds
only ever pulled a commemorated *sanctoral* id's own readings, never a
commemorated *temporal* one's -- so a commemorated Ember day (the common
case) would never have surfaced its own content. Same root cause as the
day.winner.id gap the IHM relocation fixed earlier, just hiding in the
commemorations loop instead.

Authored all 6 days' real collect + 3 Matins readings each, transcribed
directly from the reference engine (September: Tempora/093-{3,5,6}.txt;
Advent: Tempora/Adv3-{3,5,6}.txt, whose lessons are themselves a
cross-reference to the Annunciation's own Common, followed and
transcribed from there). Kept as 3 separate readings per day rather than
the usual combine-into-one default, since each carries its own
genuinely distinct proper responsory.

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

TODO.md

@@ -2368,6 +2368,75 @@ today.
 No behavior change — `tests/calendar/immaculate-heart-of-mary.test.ts` (unchanged) still passes
 end-to-end through the new generic path. `npm test` (430 tests) and `tsc --noEmit` both pass.
 
+### September + Advent Ember days — new mechanism + real content authored (2026-08-22)
+
+Follow-on from the movable-feasts generalization above: researched whether Ember days belonged
+in that same table (they don't — see below) and, once that was settled, built their actual
+mechanism and authored real Matins content for all 6 days as the first two proof cases.
+
+**Not a `movable-feasts.ts` entry.** Live-verified against the reference engine (Monastic
+Tridentinum 1617): September Ember Wednesday 2026 was won outright by Ss. Cornelius & Cyprian
+(Semiduplex) with the Ember feria demoted to `Commemoratio ad Laudes tantum` — i.e. Ember days
+are **privileged ferias**, not named feasts contesting the day by `FeastClass` rank the way
+Christ the King/Immaculate Heart of Mary do. Two separate, smaller pieces of new mechanism
+instead:
+
+- **Precedence**: `calendar/temporal.ts`'s new `septemberEmberDayOffset` (the Sunday nearest
+  Sept 14, i.e. the Exaltation of the Holy Cross, +3/+5/+6 for Wed/Fri/Sat — same "nearest"
+  arithmetic `adventStart` already used for "Sunday nearest Nov 30," factored out into a shared
+  `nearestSunday` helper) feeds a new check in `resolveTemporalCategory`, giving those 3 dates
+  `privileged-feria-minor` — live-verified as the correct tier. Advent Ember days needed **no**
+  precedence change at all: Advent's own season default is already `privileged-feria-minor`,
+  and no live evidence turned up that Advent Ember days need a stronger tier (`adventEmberDayOffset`
+  only exists for the content-id side below, not this one). Note this settles the "not
+  worth guessing at" gap flagged in `temporal-categories.yml`'s own header comment, added back
+  when this was still unmodeled.
+- **Content identity**: new `calendar/ember-days.ts`'s `applyEmberDay`, run right after
+  `applyOctaves` in `resolveDay`'s chain (same octave-guard `applyMarianSaturday` uses — the
+  Nativity of the BVM's own octave, Sep 8-15, can genuinely overlap a late-anchored September
+  Ember week in some years). When the feria itself is what's winning (no saint strong enough to
+  clear the `privileged-feria-minor` threshold), its `winner.id` is relabeled to the Ember day's
+  own id (`ember-september-wednesday`, etc.) so its real proper collect/readings are found
+  instead of inheriting whatever Sunday governs that week; when a saint wins outright instead,
+  the Ember day is pushed as a `{kind: 'temporal', ...}` commemoration alongside it (this app
+  doesn't model the "Laudes only" hour-scoping nuance the live rubric shows — same
+  simplification level as every other commemoration here).
+
+**Real bug found and fixed along the way**: `hours/matins.ts`'s `nocturnReadingIds` only ever
+pulled in a *sanctoral* commemoration's own id, never a *temporal* one's — so a commemorated
+Ember day (the common case: most Ember days lose the precedence contest to whatever saint
+occurs) would never have surfaced its own nocturn readings at all. Fixed by extending that
+check to `c.kind === 'sanctoral' || c.kind === 'temporal'`. Same root cause, same fix shape, as
+the day.winner.id gap the Immaculate Heart of Mary relocation surfaced above — this one just
+hid in the commemorations loop instead.
+
+**Content authored**: all 6 days' real collect + 3 Matins readings (Gospel-citation-plus-homily
+pattern, bare Gospel incipits skipped per this store's own established convention — see
+st-lawrence.yml/st-andrew.yml — only the homily portion transcribed), read directly from
+`Tempora/093-{3,5,6}.txt` (September) and `Tempora/Adv3-{3,5,6}.txt` (Advent, whose Lectio1-3
+are themselves a cross-reference to the Annunciation's own Common, `Sancti/03-25.txt` — followed
+and transcribed from there). Kept as 3 separate readings per day rather than combining into one
+(this store's usual default when several lessons share one continuous source) because each
+carries its own genuinely distinct, proper responsory — collapsing them would have discarded
+real, valuable content for no good reason, unlike the cases that default was written for.
+September Wednesday/Saturday use the Monastic-track's own override responsories (drawn from
+`TemporaM/093-0`'s Tobias-sermon texts) in place of the secular ones, per this project's
+Monastic-1617-first structure preference — Friday and both Advent Ember days are identical in
+both tracks (no `TemporaM/Adv3-{3,5,6}` override files exist at all).
+
+**Not authored, logged instead**: the Ember-day-specific `[Ant 2]`/`[Ant 3]` Lauds antiphons
+found during research — scoped out deliberately, same "collect + Matins first, other hours
+later" incremental pattern used throughout this project's sanctoral sweep. Also not modeled:
+the Monastic track's fuller 12-lesson/12-responsory Matins structure (a 12th responsory exists
+in the source for all 3 September days) — this app's reading-pool mechanism doesn't preserve a
+literal historical lesson count for any day, sanctoral or temporal alike, so this isn't a new
+gap specific to Ember days.
+
+New `tests/calendar/ember-days.test.ts` covers the precedence contest (September, live-verified
+saint-wins-Ember-commemorated cases) and content resolution (Advent, wins-outright cases; real
+verified Matins content on all 6 days) end-to-end. `npm test` (435 tests) and `tsc --noEmit`
+both pass.
+
 ## Known, deliberate simplifications (not bugs — working as designed)
 
 - `getDayCollects`: each collect in a multi-collect day renders as its own