Model St. Clare and surface active octaves in the day label

Today (Aug 12, within St. Lawrence's octave) was resolving as a plain
ferial day: St. Clare wasn't modeled in the calendar at all, and even
once an octave commemoration exists, getDayLabel only ever looked for a
sanctoral commemoration, never an octave one, so the label fell all the
way through to the generic ordinal week label.

Adds St. Clare (Simplex under Monastic 1617, correctly losing to
Lawrence's octave and only commemorated -- live-verified against three
clean years). Extends getDayLabel to show the active octave itself as
the day's primary identity when nothing else has won outright (e.g.
"3rd Day within the Octave of St. Lawrence, Martyr -- St. Clare,
Virgin"), matching what the live reference engine actually titles these
days, rather than falling back to an anonymous ordinal week label.

Also fixes a regression this surfaced: Trinity Sunday is technically
also day 8 of Pentecost's own octave, and the naive octave-first check
was shadowing its own anchor-day name ("8th Day within the Octave of
Pentecost" instead of "Trinity Sunday"). A season's own named anchor day
now always outranks an active octave label.

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

src/data/calendar/saints/st-clare.yml

@@ -0,0 +1,17 @@
+# Verified against Divinum Officium (Monastic Tridentinum 1617), live
+# Lauds query (2026/2027/2028-08-12, all clean years with no Sunday
+# collision) -- always commemorated, never wins outright: St. Lawrence's
+# own octave (Aug 10-17, semiduplex threshold) reliably takes the day
+# from her ("Tertia die infra Octavam S. Laurentii Martyris ~
+# Semiduplex", with "Commemoratio: S. Claræ Virginis"). Her own rank here
+# is the Monastic-specific one (the raw file's "sed rubrica 1570 aut
+# rubrica ^Monastica" branch, Simplex) rather than the later, higher
+# Roman/secular Duplex given alongside it in the same file -- consistent
+# with this app's general Monastic-track sourcing discipline.
+# No unique collect/antiphon authored yet -- one of the remaining
+# `propers: null` saints (see TODO.md).
+id: st-clare
+name: "St. Clare, Virgin"
+rank: simplex
+common: common-of-a-virgin
+propers: null

src/data/calendar/sanctoral-calendar.yml

@@ -182,6 +182,7 @@ days:
   "08-08": [ss-cyriacus-largus-and-smaragdus]
   "08-09": [vigil-of-st-lawrence, st-romanus]
   "08-10": [st-lawrence]
+  "08-12": [st-clare]
   "08-15": [assumption]
   "08-20": [st-bernard]
   "08-23": [vigil-of-st-bartholomew]