feat(ef): implement RG 33's third omission trigger

RG 33 omits a II/III-class vigil in three cases: it falls on a Sunday, it
falls on a I-class feast, "vel si festum cui praemittitur in alium diem
transferri aut ad commemorationem reduci contingat". Only the first two
were built; the third was recorded in precedence_ef.ml as unimplemented on
the grounds that no witness existed in the shipped data. That reasoning was
wrong, and the rule fires on 1 744 days across 1583-9999.

Both halves of the clause reduce to one observable question -- is the feast
the OBSERVED office on the following day (RG 34 puts it there) -- so the
kernel asks it once per candidate, after place_transfers has settled the
year. No fixed point is needed: a vigil is a candidate only on its own day,
never on its feast's, so suppressing it cannot change what the next day
observes. Precedence.rules gains vigil_feast, which returns the slug of the
feast a vigil precedes; the kernel cannot infer that itself, because only
two of the five vigil/feast pairs share a slug stem.

Blast radius, measured pre-change binary vs HEAD over the whole domain and
classified: 1 744 days, three shapes, zero unexplained. 1 199 are the feast
reduced to a commemoration (10 August on a Sunday, St Lawrence); 478 and 67
are the feast transferred under RG 96 after the Sacred Heart or Corpus
Christi takes its day. The Assumption's and the Ascension's vigils never
qualify -- their I-class feasts always keep their own day.

Independently witnessed, which is unusual here. The published Ordo -- the
only witness outside the Divinum Officium -> missalemeum -> lectio lineage
-- omits St Lawrence's vigil on 2025-08-09, agreeing with colitur against
both engines. That date had been read earlier as an Ordo gap; the Ordo was
right, and correcting the misreading is what surfaced this clause. On
2027-08-09 the feast does keep its day and the Ordo omits a vigil colitur
correctly keeps, which is a genuine Ordo gap.

Allow-lists: C39 (lectio, 10 rows) and a 2038 oracle class citing the
register, the 2026-2027 window having no instance. The golden pin asserting
St Lawrence's vigil is violet moved 2025 -> 2027; its own comment had
reasoned about the vigil's weekday and missed that RG 33 also looks at the
feast's. Two new pins cover both shapes of the clause.

The vigil/feast table is built with Slug.of_string_exn: mutation testing
showed that of_string plus Result.to_option turns a typo into None, which
this hook's contract reads as "not a vigil", switching the rule off in
silence. Two tests assert the table against the shipped data in both
directions.

1 files changed, 6 insertions, 6 deletions

diff --git a/test/test_validate.ml b/test/test_validate.ml
index 4d5458f..8b3014a 100644
--- a/test/test_validate.ml
+++ b/test/test_validate.ml
@@ -247,7 +247,7 @@ module Synthetic = struct
      fixtures further down override [rules] (and supply a non-empty
      [layer]), each with its own small, deliberately-shaped ruleset. *)
   let rules : (season, rank) P.rules =
-    { P.band = (fun _ _ -> 0);
+    { P.vigil_feast = (fun _ -> None); band = (fun _ _ -> 0);
       disposition = (fun ~winner:_ ~loser:_ -> P.Omit);
       admit = (fun ~observed:_ ~temporal:_ _ -> []) }
 
@@ -425,7 +425,7 @@ module Synthetic = struct
   let dup_layer = Layer.of_entries ~id:"dup" ~name:"dup" [ dup_entry ]
 
   let dup_rules : (season, rank) P.rules =
-    { P.band = (fun _ c -> match c.P.origin with P.Temporal -> 0 | P.Sanctoral -> 10);
+    { P.vigil_feast = (fun _ -> None); band = (fun _ c -> match c.P.origin with P.Temporal -> 0 | P.Sanctoral -> 10);
       disposition = (fun ~winner:_ ~loser:_ -> P.Commemorate P.Ordinary);
       admit =
         (fun ~observed:_ ~temporal:_ cs ->
@@ -464,7 +464,7 @@ module Synthetic = struct
   let guard_layer = Layer.of_entries ~id:"guard" ~name:"guard" [ guard_winner_entry; guard_loser_entry ]
 
   let guard_rules : (season, rank) P.rules =
-    { P.band = (fun _ c -> match c.P.origin with P.Temporal -> 50 | P.Sanctoral -> 10);
+    { P.vigil_feast = (fun _ -> None); band = (fun _ c -> match c.P.origin with P.Temporal -> 50 | P.Sanctoral -> 10);
       disposition =
         (fun ~winner:_ ~loser ->
           match loser.P.cel.Cel.rank with R1 -> P.Transfer | R2 -> P.Commemorate P.Ordinary);
@@ -493,7 +493,7 @@ module Synthetic = struct
     | x :: xs -> if n <= 0 then [] else x :: adm_take (n - 1) xs
 
   let adm_rules : (season, rank) P.rules =
-    { P.band = (fun _ c -> match c.P.origin with P.Temporal -> 0 | P.Sanctoral -> 10);
+    { P.vigil_feast = (fun _ -> None); band = (fun _ c -> match c.P.origin with P.Temporal -> 0 | P.Sanctoral -> 10);
       disposition = (fun ~winner:_ ~loser:_ -> P.Commemorate P.Ordinary);
       admit =
         (fun ~observed:_ ~temporal:_ cs ->
@@ -520,7 +520,7 @@ module Synthetic = struct
   let collide_layer = Layer.of_entries ~id:"collide" ~name:"collide" [ collide_a_entry; collide_b_entry ]
 
   let collide_rules : (season, rank) P.rules =
-    { P.band =
+    { P.vigil_feast = (fun _ -> None); band =
         (fun ctx c ->
           match c.P.origin with
           | P.Temporal -> if D.compare ctx.P.date collide_d1 = 0 then 5 else 50
@@ -543,7 +543,7 @@ module Synthetic = struct
   let clean_sanctoral_layer = Layer.of_entries ~id:"clean" ~name:"clean" [ clean_sanctoral_entry ]
 
   let clean_sanctoral_rules : (season, rank) P.rules =
-    { P.band = (fun _ c -> match c.P.origin with P.Temporal -> 0 | P.Sanctoral -> 10);
+    { P.vigil_feast = (fun _ -> None); band = (fun _ c -> match c.P.origin with P.Temporal -> 0 | P.Sanctoral -> 10);
       disposition = (fun ~winner:_ ~loser:_ -> P.Commemorate P.Ordinary);
       admit = (fun ~observed:_ ~temporal:_ cs -> List.map (fun (c, p, (_ : int)) -> (c, p)) cs) }
 end