Add St. Juan Diego (Dec 9)

Sourced from the reference engine's national-calendar file (canonized
2002, outside both Tridentine 1906 and Divino Afflatu 1954). Source
rank "Duplex optional" has no FeastClass slot; mapped to Duplex then
deflated one tier to Semiduplex per the late-canonization rule. Live-
verified he's actually a commemoration, not the day's winner: Dec 9
falls inside the Immaculate Conception octave, whose elevated
wins:duplex threshold outranks a plain Semiduplex.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwsZQMjALCvy7u9tFDWmuQ

src/data/calendar/saints/st-juan-diego.yml

@@ -0,0 +1,29 @@
+# Read directly from the reference engine: Sancti/12-09n.txt --
+# "S. Juan Diego;;Duplex optional;;2.5;;vide C5" (Common of a Confessor
+# Not a Bishop) -- an `n` (national-calendar) file, not part of either
+# Tridentine 1906 or Divino Afflatu 1954 (canonized 2002, added to the
+# Mexican/US calendars afterward). "Duplex optional" isn't a real
+# historical rank at all (a post-Vatican-II ranking concept vu's
+# FeastClass scale has no slot for) -- mapped here to an ordinary Duplex
+# first, then deflated one tier to Semiduplex per the standing
+# late-canonization rule (St. Rose of Lima precedent, CLAUDE.md). Live
+# resolveDay check (2026-12-09): Semiduplex alone would clear
+# privileged-feria-minor's own threshold, but Dec 9 falls within the
+# Immaculate Conception's octave, whose elevated `wins: duplex`
+# threshold (calendar/octaves.ts) outranks a plain Semiduplex -- so he's
+# demoted to a commemoration and the Advent feria keeps the day, same
+# actual behavior as St. Damasus at Dec 11 (that file's own header
+# comment predates the octave-wins-class rework and is stale on this
+# point). No unique collect/antiphon in the source -- Common of a
+# Confessor Not a Bishop only, same profile as st-hyacinth.yml.
+id: st-juan-diego
+name: "St. Juan Diego, Confessor"
+rank: semiduplex
+common: common-of-a-confessor
+propers: null
+collectCommon: collect-c5
+collectName:
+  la: ["Joánnis Dídaci"]
+  en: ["Juan Diego"]
+benedictusCommon: common-of-a-confessor
+minorHoursCommon: common-of-a-confessor

src/data/calendar/sanctoral-calendar.yml

@@ -466,6 +466,7 @@ days:
   "12-06": [st-nicholas]
   "12-07": [st-ambrose]
   "12-08": [immaculate-conception]
+  "12-09": [st-juan-diego]
   "12-10": [st-melchiades]
   "12-11": [st-damasus]
   "12-13": [st-lucy]