fix(cli): render the Second reading on colitur readings

The OF lectionary (data/of/lectionary.sexp) carries 183 Second readings,
146 of them on Sunday keys, and the kernel resolves them correctly -- but
readings_line (EF) and readings_line_of (OF) in bin/main.ml only ever
printed Citation.First and Citation.Gospel, so `colitur readings --rite of`
silently dropped every Second reading it computed.

Both functions gain a second_suffix lookup, spliced between the existing
First and Gospel fields, present only when the day carries a Second
citation. No rite check: EF's citation_shapes is [[First; Gospel]] alone,
so EF rows are unaffected by construction, not by special-casing.

EF byte-identity verified two ways: `git diff --stat v1.0.0..HEAD --
data/ef/` is empty, and `colitur day`/`colitur readings --rite ef` for
2026, 1583 and 9999 cmp identical against a build of the prior commit.

test/cli.t: fixed the one now-stale assertion and added coverage for the
three-citation OF Sunday shape alongside the unchanged two-citation OF
weekday and EF shapes.

1 files changed, 35 insertions, 2 deletions

diff --git a/bin/main.ml b/bin/main.ml
index eab41d8..6e3b03c 100644
--- a/bin/main.ml
+++ b/bin/main.ml
@@ -473,13 +473,32 @@ let readings_line ~lang ~sigla (d : (Rite_ef.Vocab_ef.season, Rite_ef.Vocab_ef.r
     | Some c -> Colitur_citation.Sigla.format sigla c.Colitur_kernel.Citation.reference
     | None -> "-"
   in
+  (* The Second reading (OLM n. 67: a Sunday/solemnity's own three-reading
+     shape) is present-or-absent, not present-or-"-": unlike First/Gospel
+     ({!Colitur_kernel.Validate}'s "citations" check guarantees exactly one
+     of each on every day of every rite), a day may legitimately carry no
+     Second reading at all ([Rite.t.citation_shapes] for EF is
+     [[First; Gospel]] alone), and EF never carries one. So this is an
+     append-only field, the same discipline [name_suffix] below already
+     uses -- absent, it contributes the empty string and this row is
+     byte-identical to what it printed before the Second reading existed. *)
+  let second_suffix =
+    match
+      List.find_opt
+        (fun (c : Colitur_kernel.Citation.t) -> c.Colitur_kernel.Citation.part = Colitur_kernel.Citation.Second)
+        d.Colitur_kernel.Liturgical_day.citations
+    with
+    | Some c -> " | " ^ Colitur_citation.Sigla.format sigla c.Colitur_kernel.Citation.reference
+    | None -> ""
+  in
   let slug_s = Colitur_kernel.Slug.to_string cel.Colitur_kernel.Celebration.slug in
   let name = Colitur_naming.Lang.celebration lang slug_s in
   let name_suffix = if name = slug_s then "" else " | " ^ name in
-  Printf.printf "%s %s | %s | %s%s\n"
+  Printf.printf "%s %s | %s%s | %s%s\n"
     (D.to_iso8601 d.Colitur_kernel.Liturgical_day.date)
     slug_s
     (part_ref Colitur_kernel.Citation.First)
+    second_suffix
     (part_ref Colitur_kernel.Citation.Gospel)
     name_suffix
 
@@ -736,13 +755,27 @@ let readings_line_of ~lang ~sigla
     | Some c -> Colitur_citation.Sigla.format sigla c.Colitur_kernel.Citation.reference
     | None -> "-"
   in
+  (* Second reading: present-or-absent, not present-or-"-" -- see
+     [readings_line]'s own comment for the full reasoning (OLM n. 67, a
+     Sunday/solemnity's own three-reading shape; [Rite.t.citation_shapes]
+     is what actually distinguishes which OF days carry one). *)
+  let second_suffix =
+    match
+      List.find_opt
+        (fun (c : Colitur_kernel.Citation.t) -> c.Colitur_kernel.Citation.part = Colitur_kernel.Citation.Second)
+        d.Colitur_kernel.Liturgical_day.citations
+    with
+    | Some c -> " | " ^ Colitur_citation.Sigla.format sigla c.Colitur_kernel.Citation.reference
+    | None -> ""
+  in
   let slug_s = Colitur_kernel.Slug.to_string cel.Colitur_kernel.Celebration.slug in
   let name = observed_name_of ~lang cel slug_s in
   let name_suffix = if name = slug_s then "" else " | " ^ name in
-  Printf.printf "%s %s | %s | %s%s\n"
+  Printf.printf "%s %s | %s%s | %s%s\n"
     (D.to_iso8601 d.Colitur_kernel.Liturgical_day.date)
     slug_s
     (part_ref Colitur_kernel.Citation.First)
+    second_suffix
     (part_ref Colitur_kernel.Citation.Gospel)
     name_suffix