Milestone 0/1: shell, calendar/psalter/hours scaffold, Prime

Client-side-first PWA (Vite/TS, no backend) per the approved plan: day-
navigable shell listing all 8 hours, Prime fully resolves via the
calendar -> psalter -> ordo pipeline, the other 7 hours are registered
but flagged not-implemented. Sanctoral/temporal calendar data uses a
day -> id indirection layer (saints, easter-offsets, fixed-date-calendar)
so reassigning a feast to a different day is a data edit, not a code
change. Docker (Caddy-serving-static) + Gitea CI workflow scaffolded to
match the eec/drip/bookshop operational pattern.

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

src/calendar/commemorations.ts

@@ -0,0 +1,5 @@
+// Precedence/occurrence rules for when a lower-ranked feast is commemorated
+// rather than fully displaced by the day's winning feast. Deliberately not
+// designed yet — see plan point 5 ("calendar rules are expected to iterate").
+// Unused until milestone 4.
+export {};