Prepend R. to nocturn-readings responsories missing their opening marker

All 53 nocturn-readings files with a responsory field started straight
into the text with no leading R., unlike octave-readings' own R./V.
convention. Fixed in content per direct instruction (not injected at
render time), matching each file's own existing plain V./R. style rather
than switching to octave-readings' R./V. glyphs.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EWzE3kaSZCs79fPBrrE1aF

src/data/propers/nocturn-readings/month-week-092.yml

@@ -77,6 +77,6 @@ readings:
         man should see, that even if one had received the gifts of perfection, and were to make them
         the grounds of self-glorifying, such an one would thereby lose all that he had received.
     responsory:
-      la: "Indúta est caro mea putrédine, et sórdibus púlveris cutis mea áruit et contrácta est: * Meménto mei, Dómine, quóniam ventus est vita mea.\nV. Dies mei velócius transiérunt quam a texénte tela succíditur, et consúmpti sunt absque ulla spe.\nR. Meménto mei, Dómine, quóniam ventus est vita mea."
-      en: "My flesh is clothed with worms and clods of dust. My skin is dry and drawn together. * Remember me, O Lord, for my life is wind.\nV. My days are swifter than a weaver's shuttle, and are spent without hope.\nR. Remember me, Lord, for my life is wind."
+      la: "R. Indúta est caro mea putrédine, et sórdibus púlveris cutis mea áruit et contrácta est: * Meménto mei, Dómine, quóniam ventus est vita mea.\nV. Dies mei velócius transiérunt quam a texénte tela succíditur, et consúmpti sunt absque ulla spe.\nR. Meménto mei, Dómine, quóniam ventus est vita mea."
+      en: "R. My flesh is clothed with worms and clods of dust. My skin is dry and drawn together. * Remember me, O Lord, for my life is wind.\nV. My days are swifter than a weaver's shuttle, and are spent without hope.\nR. Remember me, Lord, for my life is wind."
     status: { la: verified, en: verified }