Normalize versicle notation to plain V./R. across propers

Unicode ℣/℟ (U+2123/U+211F) were mixed unpredictably with plain V./R.
across ~550 proper YAML files, sometimes within the same file. Screen
readers can't announce the unicode glyphs. Replace all instances with
plain text.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QC6jHsj75xcsTkapqJR6fD

src/data/propers/common/nativity-bvm-collect.yml

@@ -6,12 +6,12 @@ text:
     Orémus.
     Fámulis tuis, quǽsumus, Dómine, cæléstis grátiæ munus impertíre: ut, quibus beátæ Vírginis partus éxstitit salútis exórdium; Nativitátis ejus votíva solémnitas pacis tríbuat increméntum.
     Per Dóminum nostrum Jesum Christum, Fílium tuum: qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus, per ómnia sǽcula sæculórum.
-    ℟. Amen.
+    R. Amen.
   en: |
     Let us pray.
     Grant unto us thy servants, we beseech thee, O Lord, the gift of thy heavenly grace, unto whom Thou didst give the first sight of a Saviour as the offspring of a Blessed Virgin, and grant that this Feast, which they keep in honour of the same Virgin, may avail them unto the increase of peace.
     Through Jesus Christ, thy Son our Lord, Who liveth and reigneth with thee, in the unity of the Holy Ghost, God, world without end.
-    ℟. Amen.
+    R. Amen.
 status:
   la: verified
   en: verified