calendar: split privileged-feria into two real precedence tiers

A plain Duplex saint was losing to any privileged feria (Ember days
included) since the occurrence engine only let duplex-1-classis+ get
even a commemoration there. Verified this was wrong: St. Gregory the
Great, plain Duplex, outright wins against a Lenten Ember Saturday in
the real Monastic 1617 engine.

Splits TemporalCategory's single privileged-feria into privileged-feria
(the lesser tier — Lent's Ember days, verified — now behaves like an
ordinary Sunday: Duplex+ wins outright) and privileged-feria-major (Ash
Wednesday, Holy Week, the Easter Octave, verified via St. Mark only ever
being commemorated there, never winning — behaves like privileged-
Sunday). Everywhere else the old single category was ambiguous
(Pentecost's own Ember days/Vigil/Octave, the Vigil of Christmas)
defaults to the stricter major tier pending verification.

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

src/calendar/types.ts

@@ -70,7 +70,24 @@ export type FeastClass =
 // category — reconstructed from general knowledge of the pre-1955
 // tradition, not yet verified against a primary source, so expect
 // corrections.
-export type TemporalCategory = 'ordinary-feria' | 'privileged-feria' | 'ordinary-sunday' | 'privileged-sunday';
+// `privileged-feria` and `privileged-feria-major` are two real, distinct
+// tiers (confirmed by finding a plain Duplex saint, St. Gregory the Great,
+// outright winning against a Lenten Ember Saturday in the real Monastic
+// 1617 engine, which the original single-tier model wrongly forbade) —
+// see calendar/commemorations.ts's rules for `privileged-feria` (behaves
+// like `ordinary-sunday`: Duplex+ wins outright) vs `privileged-feria-major`
+// (behaves like `privileged-sunday`: never displaced at all, confirmed by
+// checking St. Mark, Duplex II. classis, merely commemorated rather than
+// winning within the Easter Octave). See data/calendar/temporal-
+// categories.yml for exactly which days fall in which tier — some of that
+// split (e.g. whether Pentecost's own Ember days share Lent's lesser tier
+// or Easter's major one) is still a reconstructed guess, not verified.
+export type TemporalCategory =
+  | 'ordinary-feria'
+  | 'privileged-feria'
+  | 'privileged-feria-major'
+  | 'ordinary-sunday'
+  | 'privileged-sunday';
 
 export interface SanctoralIdentity {
   id: string;