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/hours/types.ts

@@ -61,6 +61,12 @@ export type HourPart =
       resolvedKind: 'chapter' | 'preces';
       label?: string;
       omitOnDouble?: true;
+      // When true, a Vigil-ranked sanctoral winner takes the ferialRef
+      // instead of the sundayOrFeastRef isSundayOrFeastOffice would
+      // otherwise give it (that function treats any sanctoral winner,
+      // Vigils included, as a "feast"). Prime's Preces use this; its
+      // capitulum doesn't.
+      vigilIsFerial?: true;
       sundayOrFeastRef: PropersRef;
       ferialRef: PropersRef;
     }