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/ss-nereus-achilleus-domitilla-and-pancras-commemoration.yml

@@ -13,7 +13,7 @@ text:
     Orémus.
     Semper nos, Dómine, Mártyrum tuórum Nérei, Achíllei, Domitíllæ atque Pancrátii fóveat, quǽsumus, beáta solémnitas: et tuo dignos reddat obséquio.
     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: |
     Ant. Daughters of Jerusalem, * come and see the crowned martyrs, the Lord crowned them in his solemnity and delight, alleluia, alleluia.
     V. The saints shall rejoice in glory:
@@ -21,7 +21,7 @@ text:
     Let us pray.
     May the holy feast of thy Martyrs, Nereus, Achilleus, Domitilla and Pancras, ever comfort us, we beseech thee, O Lord, and make us worthy to serve thee.
     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