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

src/data/propers/temporal/ember-advent-wednesday-collect.yml

@@ -0,0 +1,19 @@
+# Read directly from web/www/horas/Latin/Tempora/Adv3-3.txt's own [Oratio]
+# and its English counterpart. Standard "Per Dóminum..." closing spelled
+# out in full (the source abbreviates it), matching every other collect
+# in this store.
+id: ember-advent-wednesday-collect
+text:
+  la: |
+    Orémus.
+    Præsta, quǽsumus, omnípotens Deus: ut redemptiónis nostræ ventúra solémnitas et præséntis nobis vitæ subsídia cónferat, et ætérnæ beatitúdinis prǽmia largiátur.
+    Per Dóminum nostrum Jesum Christum, Fílium tuum: qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus, per ómnia sǽcula sæculórum.
+    R. Amen.
+  en: |
+    Let us pray.
+    Grant, we beseech thee, Almighty God, that the solemn Feast of our redemption, which is now at hand, may both help us in the life which now is, and further us toward the attaining of thine eternal joy in that which is to come.
+    Through Jesus Christ, thy Son our Lord, Who liveth and reigneth with thee, in the unity of the Holy Ghost, God, world without end.
+    R. Amen.
+status:
+  la: verified
+  en: verified