kernel: carry omitted celebrations on Liturgical_day.t, reason and all

Precedence.resolution already tracked what happened to every losing
candidate -- commemorated, deferred, or omitted with a reason -- but
Liturgical_day.t had nowhere for the deferred and omitted buckets to land,
so Calendar dropped them at the door. Task 12's no-celebration-lost
invariant needs to read that accounting off the day result itself, not
re-resolve every day to reconstruct it, so a reason recorded nowhere is not
recorded.

Add Liturgical_day.omitted : ('r Celebration.t * string) list, after
transferred_out and before citations. Calendar.resolve_day now folds
resolution.omitted (Precedence's own native omissions, reasons intact) and
resolution.deferred (mapped to "deferred: transfer placement not yet
implemented (Task 6)") into it.

Adds a full-day accounting test against the whole Calendar pipeline: four
colliding sanctoral entries plus the day's feria, checked as a slug set
(matching test_precedence.ml's own nothing-silently-lost test) so a
candidate silently dropped or duplicated into two buckets would fail it,
plus an identity check that the deferred and admission-limit reasons don't
get swapped.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/kernel/liturgical_day.ml b/lib/kernel/liturgical_day.ml
index 65e3ba5..cbaca9c 100644
--- a/lib/kernel/liturgical_day.ml
+++ b/lib/kernel/liturgical_day.ml
@@ -14,6 +14,9 @@ type ('s, 'r) t = {
       (** arrived here from an impeded day *)
   transferred_out : Date.t option;
       (** this day's celebration went there *)
+  omitted : ('r Celebration.t * string) list;
+      (** with the reason, never silent -- Task 12's no-celebration-lost
+          invariant reads this *)
   citations : Citation.t list;  (** always empty until Plan 4 *)
 }
 [@@deriving sexp]