hours: build Terce, Sext, and None

Three separate resolver files (terce.ts/sext.ts/none.ts), not a shared
little-hour module — they're structurally identical but kept independent
by choice. Ordo verified against Divinum Officium (Monastic Tridentinum
1617): opening versicle, self-contained hymn, one antiphon framing three
psalms (no closing repeat, unlike Prime), a capitulum with its own
embedded short versicle/response, the day's own collect, and a closing
identical across all three hours.

Also fills in psalter-distribution.yml's previously-missing Sunday/
Monday/Tuesday psalm entries (Ps 118 sections for Sunday/Monday; Tuesday
turns out to share Wednesday/Thursday's native gradual-psalm set, not a
distinct one). Friday/Saturday's antiphons are derived from each day's
first psalm rather than reusing the native gradual antiphons, since
those two days already use a redistributed, non-native psalm set.

hours/types.ts gains a 'day-collect' part kind — the first ordo to use
the day's own Proper collect rather than a fixed text.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/hours/types.ts

@@ -87,7 +87,13 @@ export type HourPart =
   // Salve Regina. See hours/marian-antiphon.ts.
   | { kind: 'marian-antiphon' }
   // Unused by Prime/Compline/the little hours — exercised starting milestone 4.
-  | { kind: 'variable'; resolve: 'by-weekday' | 'by-season' | 'by-feast-rank' };
+  | { kind: 'variable'; resolve: 'by-weekday' | 'by-season' | 'by-feast-rank' }
+  // The day's own Proper-of-season/Proper-of-saints collect — resolved by
+  // day, not by textRef. First used by the Little Hours' "Oratio {ex
+  // Proprio de Tempore}" via hours/resolve-common.ts's getDayCollect;
+  // Prime/Compline both still use a fixed collect (`prayer` + textRef).
+  // Renders as a plain 'prayer' ResolvedPart.
+  | { kind: 'day-collect' };
 
 export interface HourDefinition {
   id: HourId;