Give Prime's Preces the ferial form on Vigil days

isSundayOrFeastOffice treats any sanctoral winner, Vigils included, as a
"feast," so a Vigil day was getting the Sunday/feast Preces. Add a
by-day-kind 'vigilIsFerial' flag, set only on Prime's Preces part (its
capitulum keeps the old behavior), so a Vigil-ranked winner now routes
to the ferial Preces text instead.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HWN869GrMFHqrer9fdCBbF

src/data/hours/prime.yml

@@ -30,6 +30,12 @@
 # ferial Preces are said on *every* ferial day, not just Advent/Lent/
 # vigils/Ember days the way later rubrics restricted them.
 #
+# Preces additionally set `vigilIsFerial: true` — isSundayOrFeastOffice on
+# its own treats any sanctoral winner, Vigils included, as a "feast," but
+# by explicit choice a Vigil day gets the ferial Preces instead. The
+# capitulum doesn't set this flag, so a Vigil still gets the Sunday/feast
+# capitulum, same as before.
+#
 # Preces deliberately use the *secular* Tridentine form
 # (propers/common/prime-preces-dominicales.yml), not Monastic Prime's own
 # shorter Dominicales form — chosen because the secular form keeps content
@@ -65,6 +71,7 @@ parts:
   - kind: by-day-kind
     resolvedKind: preces
     omitOnDouble: true
+    vigilIsFerial: true
     sundayOrFeastRef: { source: common, id: prime-preces-dominicales }
     ferialRef: { source: common, id: prime-preces-feriales }
   - kind: prayer