propers: add June's collect and antiphon text

Real collect text for all 16 June saints that have one, plus a real
antiphon for 4 of them and a fifth (Ss. Peter and Paul) that deliberately
reuses the Chair-of-Peter-at-Antioch antiphon text, matching the source's
own cross-reference — same extraction method as prior months.

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

src/data/propers/common/st-barnabas-collect.yml

@@ -0,0 +1,18 @@
+# Verified against Divinum Officium (Monastic Tridentinum 1617) — read
+# directly from the reference engine's own real-date output (2035-06-11).
+# Same convention as data/propers/temporal/*-collect.yml.
+id: st-barnabas-collect
+text:
+  la: |
+    Orémus.
+    Deus, qui nos beáti Bárnabæ Apóstoli tui méritis et intercessióne lætíficas: concéde propítius; ut, qui tua per eum benefícia póscimus, dono tuæ grátiæ consequámur.
+    Per Dóminum nostrum Jesum Christum, Fílium tuum: qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus, per ómnia sǽcula sæculórum.
+    ℟. Amen.
+  en: |
+    Let us pray.
+    O God, Who dost gladden us through the worthy deeds and prayers of thy blessed apostle Barnabas, mercifully grant that all they which seek thy mercy through him may effectually obtain the gift of thy grace.
+    Through Jesus Christ, thy Son our Lord, Who liveth and reigneth with thee, in the unity of the Holy Ghost, God, world without end.
+    ℟. Amen.
+status:
+  la: verified
+  en: verified