Add June sanctoral content: 6 saints

Continues the full-year sanctoral import: St. Angela Merici, St. Francis
Caracciolo, St. Boniface of Mainz (Bishop and Martyr, Apostle of Germany --
distinct from the earlier, unrelated St. Boniface Martyr already on May 14),
St. Norbert, St. Margaret of Scotland, and St. Aloysius Gonzaga.

Two of the new fixed dates (June 1, June 4) fall on dates used by two
day-label tests pinned to specific Trinity Sunday years; moved those to
years/dates free of the new entries, with explanatory comments.

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

src/data/calendar/sanctoral-calendar.yml

@@ -151,8 +151,13 @@ days:
   # (the 4th day of St. John the Baptist's octave) is a pure temporal
   # continuation with no named secondary saint, so it's excluded, same as
   # every other octave-continuation day this pull has skipped.
+  "06-01": [st-angela-merici]
   "06-02": [ss-marcellinus-peter-and-erasmus]
+  "06-04": [st-francis-caracciolo]
+  "06-05": [st-boniface-of-mainz]
+  "06-06": [st-norbert]
   "06-09": [ss-primus-and-felicianus]
+  "06-10": [st-margaret-of-scotland]
   "06-11": [st-barnabas]
   "06-12": [ss-basilides-cyrinus-nabor-and-nazarius]
   "06-13": [st-anthony-of-padua]
@@ -161,6 +166,7 @@ days:
   "06-18": [ss-mark-and-marcellian]
   "06-19": [ss-gervase-and-protase]
   "06-20": [st-silverius]
+  "06-21": [st-aloysius-gonzaga]
   "06-22": [st-paulinus-of-nola]
   "06-23": [vigil-of-st-john-the-baptist]
   "06-24": [nativity-of-st-john-the-baptist]