propers: add February's collect and antiphon text

Real collect text for the 6 February saints that have one, plus a real
antiphon for the 2 that have one of their own — same extraction method
as January (fully-rendered live-engine output, not the raw source files'
own shorthand endings).

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

src/data/propers/common/chair-of-st-peter-at-antioch-antiphon.yml

@@ -0,0 +1,14 @@
+# Verified against Divinum Officium (Latin/English Sancti/02-22.txt's own
+# [Ant 1] — this feast's true home; the Chair-of-Peter-at-Rome feast
+# (Jan 18) cross-references this same text rather than repeating it, and
+# its collect is likewise identical to this feast's own (see
+# chair-of-st-peter-at-rome-collect.yml / chair-of-st-peter-at-antioch-
+# collect.yml — deliberately duplicated content, not a shared reference,
+# matching this project's one-file-per-id convention).
+id: chair-of-st-peter-at-antioch-antiphon
+text:
+  la: "Tu es pastor óvium, * Princeps Apostolórum, tibi tráditæ sunt claves regni cælórum."
+  en: "Thou art the Shepherd * of the sheep, and the Prince of the Apostles, and unto thee are given the keys of the kingdom of heaven."
+status:
+  la: verified
+  en: verified