Add Matins tests; update tests that assumed it was still a stub

tests/hours/matins.test.ts covers both branches (ferial, Sunday)
end-to-end through the real resolveOrdo mechanism against two clean,
live-verified dates — psalm/canticle counts, Te Deum presence, reading
citations/statuses, Gospel flagging and its Common-fallback exclusion,
and responsory matching.

tests/hours/prime.test.ts and tests/ui/shell.test.ts both had assertions
that Matins was still pending — replaced with assertions that it now
renders real content, mirroring the equivalent Compline test.

tests/hours/prime.test.ts

@@ -224,11 +224,3 @@ describe('resolveOrdo("prime", ...)', () => {
     }
   });
 });
-
-describe('resolveOrdo for not-yet-built hours', () => {
-  it('flags matins as not implemented rather than throwing', () => {
-    const ordo = resolveOrdo('matins', MONDAY);
-    expect(ordo.notImplemented).toBe(true);
-    expect(ordo.parts).toEqual([]);
-  });
-});