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/ui/day-nav.ts

@@ -0,0 +1,17 @@
+import { getState, shiftDate, goToToday } from '../app-state';
+import { formatDateLong } from './format';
+
+export function renderDayNav(container: HTMLElement): void {
+  const { date } = getState();
+  container.innerHTML = `
+    <nav class="day-nav" aria-label="Day navigation">
+      <button type="button" class="day-nav-btn" data-action="prev" aria-label="Previous day">&larr;</button>
+      <button type="button" class="day-nav-btn day-nav-today" data-action="today">Today</button>
+      <span class="day-nav-date">${formatDateLong(date)}</span>
+      <button type="button" class="day-nav-btn" data-action="next" aria-label="Next day">&rarr;</button>
+    </nav>
+  `;
+  container.querySelector('[data-action="prev"]')?.addEventListener('click', () => shiftDate(-1));
+  container.querySelector('[data-action="next"]')?.addEventListener('click', () => shiftDate(1));
+  container.querySelector('[data-action="today"]')?.addEventListener('click', () => goToToday());
+}