calendar: real occurrence/precedence resolution (feast ranks, sanctoral content)

Replaces the FeastRank placeholder with a real ordered FeastClass (the old
pre-1955 six-level scale) and a new TemporalCategory (privileged/ordinary
Sunday/feria). calendar/commemorations.ts's decideOccurrence encodes the
actual precedence rules as explicit, commented branches per category
rather than the reference engine's own opaque numeric weights — this app
targets one ruleset, so the readability trade-off is worth it. Category
membership (data/calendar/temporal-categories.yml) is a best-effort
reconstruction of the pre-1955 tradition, not sourced from a primary text;
expect corrections.

calendar/feasts.ts resolves real sanctoral candidates, and resolveDay()
wires it all together — occurring/temporalCategory are no longer stubs.
isDoubleOrHigher (hours/antiphon.ts) is now a real comparison instead of
a hardcoded false.

Seeded 7 real saints/feasts, each verified directly against Divinum
Officium's own rank data (not reconstructed from memory) as a small,
growable start: St. Lawrence, the Assumption, St. Augustine, the Nativity
of the BVM, St. Michael, All Saints, the Immaculate Conception.

src/data/calendar/saints/example-confessor.yml

@@ -1,9 +1,8 @@
-# PLACEHOLDER — demonstrates the saint-record shape only. Not a real saint,
-# not a real rank, not a real day assignment (see sanctoral-calendar.yml for
-# where this id gets pointed at a day). Which day(s) point here can change
-# freely without ever touching this file.
+# PLACEHOLDER — demonstrates the saint-record shape only, deliberately not
+# mapped to any day in sanctoral-calendar.yml (which now holds real,
+# verified entries — see that file). Not a real saint, not a real rank.
 id: example-confessor
 name: "Example Confessor (placeholder)"
-rank: placeholder # real rank scheme is a milestone 4 decision, not made yet
+rank: simplex # placeholder value
 common: common-of-a-confessor-not-bishop
-propers: null # set to a propers id once/if this saint has a full proper
+propers: null