Add August Matins readings for SanctiM-track saints

13 of August's 16 SanctiM-track saints authored, including the Duplex
I class feasts of St. Lawrence and the Assumption of the B.V.M. The
Assumption's presence confirms this app's calendar already maps fixed
BVM feasts, despite an older note in the parent workspace CLAUDE.md
suggesting otherwise -- flagged in memory as stale documentation to
verify against, not trust blindly. 3 saints left unsourced (Common-only
or Nocturn-1-only vigil content).

src/data/propers/nocturn-readings/st-sabina.yml

@@ -0,0 +1,39 @@
+# Matins Nocturn 2 reading for St. Sabina, Martyr (Aug 29, sharing the
+# date with the Decollation of St. John the Baptist — see
+# decollation-of-st-john-baptist.yml). No genuine SanctiM match: the
+# only SanctiM files for this date base `@Sancti/08-29` (the
+# Decollation, not Sabina) — a missed pre-1955-pool candidate rather
+# than a genuine SanctiM case (see memory vu-matins-pre1955-saints,
+# vu-matins-sanctim-saints).
+# web/www/horas/Latin/Sancti/08-29cc.txt, English/Sancti/08-29cc.txt.
+# Single lesson (simplex-feast Lectio93), one continuous account, no
+# responsory given in the source.
+id: st-sabina
+readings:
+  - nocturn: 2
+    isGospel: false
+    text:
+      la: >-
+        Sabina, mulier Romana, Valentini viri claríssimi uxor, a Seráphia vírgine christianæ
+        fidei præceptis instituta, post sanctæ Vírginis martyrium, collectas ejus relíquias
+        piis exsequiis sepelívit. Quæ propter eam causam paulo post, Hadriáno imperatóre,
+        comprehensa, Elpidio júdici sistitur. Cui is: Tu ne illa Sabina et génere et matrimonio
+        nobilíssima? At illa, Sum, inquit: sed Dómino meo Jesu Christo grátias ago, qui me,
+        intercessióne Seráphiæ famulæ suæ, e dæmonum potestate liberávit. Quam varie tentatam
+        ut propositum mutaret, cum a fidei constántia movére non posset, præfectus,
+        pronuntiáta senténtia quod deos contemneret, cápitis damnávit. Ejus corpus a
+        Christiánis in eodem sepúlcro cónditum est, in quo ipsa magistram fidei suæ Seráphiam
+        posúerat.
+      en: >-
+        Sabina was a Roman lady, the wife of a distinguished nobleman named Valentine. The
+        Christian faith was taught to her by a maiden named Seraphia. After the martyrdom of
+        this holy virgin, Sabina gathered together her reliques, and buried them with godly
+        service. For this cause she was in a little while arrested, under the Emperor Hadrian,
+        and brought before the Judge Elpidius. Art thou, said he, the same Sabina who is so
+        distinguished for her blood and for her marriage? She answered: I am, but I give thanks
+        to my Lord Jesus Christ for having delivered me through the prayers of His hand-maiden
+        Seraphia from the troubling of devils. Diverse attempts were made to make her change her
+        mind, but when they proved in vain the Praefect passed sentence of death upon her for
+        despising the gods. The Christians laid her body in the same grave in which she had
+        herself laid that of Seraphia, her teacher in the faith.
+    status: { la: verified, en: verified }