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/nocturn-readings/ember-advent-saturday.yml

@@ -0,0 +1,83 @@
+# Matins Nocturn content for Advent Ember Saturday (Sabbato Quattuor
+# Temporum Adventus) — read directly from
+# web/www/horas/Latin/Tempora/Adv3-6.txt and English/Tempora/Adv3-6.txt.
+# No Monastic-track override file exists for this day — confirms the
+# Monastic 1617 track uses this same text.
+#
+# Lectio1's Gospel citation (Luke 3:1-6, the preaching of St. John the
+# Baptist) is a bare incipit with no full pericope text given, so only
+# the homily portion is authored, same convention as the other Ember
+# days. Kept as 3 separate readings, each with its own genuinely
+# distinct proper responsory.
+id: ember-advent-saturday
+readings:
+  - nocturn: 1
+    isGospel: false
+    source: "Pope St. Gregory the Great, Homily 20 on the Gospels, on Luke 3:1-6"
+    text:
+      la: >-
+        Redemptóris nostri Præcúrsor, quo témpore prædicatiónis offícium accéperit, memoráto Románæ reipúblicæ
+        príncipe, et Judǽæ régibus, designátur. Quia enim illum prædicáre veniébat, qui et ex Judǽa quosdam, et
+        multos ex géntibus redemptúrus erat: per regem géntium et príncipes Judæórum prædicatiónis ejus témpora
+        designántur. Quia autem gentílitas colligénda erat, et Judǽa pro culpa perfídiæ dispergénda, ipsa quoque
+        descríptio terréni principátus osténdit: quóniam et in Romána república unus præfuísse descríbitur, et in
+        Judǽæ regno per quartam partem plúrimi principabántur.
+      en: >-
+        The date, at which the Fore-runner of our Redeemer entered on his public office of preaching, is indicated
+        to us by the name of the ruler of the Roman Commonwealth, and by those of the princes of Palestine. The
+        time of his preaching is indicated by these names, because he came as the Fore-runner of Him Who was to be
+        the Redeemer of some Jews and many Gentiles. Moreover in the enumeration of these worldly monarchs there
+        is a foreshadowing of the fact, that the Gentiles were about to be gathered into one, and the Jews to be
+        scattered abroad in punishment of their unbelief; in the whole heathen Commonwealth we find the title of
+        one Emperor, but in the small kingdom of Judaea are mentioned four masters.
+    responsory:
+      la: "Egrediétur virga de radíce Jesse, et flos de radíce ejus ascéndet: * Et erit justítia cíngulum lumbórum ejus, et fides cinctórium renum ejus.\nV. Et requiéscet super eum spíritus Dómini: spíritus sapiéntiæ, et intelléctus: spíritus consílii, et fortitúdinis.\nR. Et erit justítia cíngulum lumbórum ejus, et fides cinctórium renum ejus."
+      en: "There shall come forth a rod out of the stem of Jesse, and a flower shall grow out of his roots. * And righteousness shall be the girdle of his loins, and faithfulness the girdle of his reins.\nV. And the Spirit of the Lord shall rest upon him the spirit of wisdom and understanding the spirit of counsel and might.\nR. And righteousness shall be the girdle of his loins, and faithfulness the girdle of his reins."
+    status: { la: verified, en: verified }
+
+  - nocturn: 2
+    isGospel: false
+    source: "Pope St. Gregory the Great, Homily 20 on the Gospels, on Luke 3:1-6"
+    text:
+      la: >-
+        Voce étenim nostri Redemptóris dícitur: Omne regnum in seípsum divisum desolábitur. Liquet ergo, quod ad
+        finem regni Judǽa pervénerat, quæ tot régibus divísa subjacébat. Apte quoque non solum quibus régibus, sed
+        étiam quibus sacerdótibus actum sit, demonstrátur: et quia illum Joánnes Baptísta prædicáret, qui simul Rex
+        et Sacérdos exsísteret, Lucas Evangelísta prædicatiónis ejus témpora per regnum et sacerdótium designávit.
+      en: >-
+        The blessed voice of the Saviour itself hath said, Every kingdom divided against itself is brought to
+        desolation. And we may well look for the ruin of the Jewish state when we see it divided among so many
+        rulers. We observe likewise that the names of the reigning priests as well as kings are given. The
+        Evangelist Luke hath left on record the chiefs both of the monarchy and of the priesthood who held office
+        when John the Baptist began to preach, because John preached Him Who is at once our Priest and our King.
+    responsory:
+      la: "Radix Jesse, qui exsúrget judicáre gentes, in eum gentes sperábunt: * Et erit nomen ejus benedíctum in sǽcula.\nV. Super ipsum continébunt reges os suum, ipsum gentes deprecabúntur.\nR. Et erit nomen ejus benedíctum in sǽcula."
+      en: "Behold, the root of Jesse that shall arise to bring forth judgment to the Gentiles, in him shall the Gentiles trust. * And his name shall be blessed for ever.\nV. The Kings shall shut their mouths at him, to him shall the Gentiles seek.\nR. And his name shall be blessed for ever."
+    status: { la: verified, en: verified }
+
+  - nocturn: 3
+    isGospel: false
+    source: "Pope St. Gregory the Great, Homily 20 on the Gospels, on Luke 3:1-6"
+    text:
+      la: >-
+        Et venit in omnem regiónem Jordánis, prǽdicans baptísmum pœniténtiæ in remissiónem peccatórum. Cunctis
+        legéntibus liquet, quia Joánnes non solum baptísmum pœniténtiæ prædicávit, verum étiam quibúsdam dedit: sed
+        tamen baptísmum suum in remissiónem peccatórum dare non pótuit. Remíssio étenim peccatórum in solo nobis
+        baptísmo Christi tribúitur. Notándum ítaque, quod dícitur: Prǽdicans baptísmum pœniténtiæ in remissiónem
+        peccatórum: quóniam baptísmum, quod peccáta sólveret, quia dare non póterat, prædicábat: ut sicut
+        incarnátum Verbum Patris præcurrébat verbo prædicatiónis, ita baptísmum pœniténtiæ, quo peccáta solvúntur,
+        præcúrreret suo baptísmate, quo peccáta solvi non possunt.
+      en: >-
+        And he came into all the country about Jordan, preaching the baptism of repentance for the remission of
+        sins. It is evident from these words that John the Baptist not only preached, but also administered the
+        baptism of repentance, and yet that baptism of repentance which he gave, was not really a baptism for the
+        remission of sins. For there is only one baptism for the remission of sins, and that is our Christian
+        baptism. It is worthy of note here that the words used are, preaching the baptism of repentance for the
+        remission of sins, for he himself owned that his baptism was not the true baptism that washes away sin.
+        Even as the Eternal Word of God made Flesh was greater than the preacher that went before Him, so was His
+        holy baptism, by which our sins are washed away, far greater than that baptism of repentance which the
+        Fore-runner preached, and which could never wash away sin.
+    responsory:
+      la: "Veni, Dómine, et noli tardáre: reláxa facínora plebi tuæ, * Et révoca dispérsos in terram suam.\nV. Excíta, Dómine, poténtiam tuam, et veni, ut salvos fácias nos.\nR. Et révoca dispérsos in terram suam."
+      en: "O Lord, come, and make no tarrying loosen the bonds of thy people. * And gather together into their own land them that are scattered abroad.\nV. Stir up, O Lord, thy power, and come among us, to save us.\nR. And gather together into their own land them that are scattered abroad."
+    status: { la: verified, en: verified }