Fix Vespers/Compline header to use evening day, not daytime day

day-nav.ts's header always resolved via resolveDay(date) regardless of
selected hour, so viewing Vespers/Compline on a day whose evening
anticipates tomorrow's First Vespers (e.g. Aug 25, 2026: St. Louis's day,
but St. Zephyrinus claims First Vespers per calendar/vespers.ts) still
showed today's saint in the header while the hour's actual content had
already switched to tomorrow's. Now uses resolveEveningDay for those two
hours specifically.

Also adds an explicit "First Vespers (of tomorrow)" / "Second Vespers (of
today)" status line to the Vespers header, via new
getVespersStatusLabel(), so the anticipation/commemoration result is
visible rather than only inferable from which saint's name shows up.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014axryJBrRswYh2niA7WCUc

src/ui/styles.css

@@ -185,6 +185,12 @@ button:focus-visible {
   color: var(--color-brass);
 }
 
+.day-nav-vespers-status {
+  font-family: var(--font-ui);
+  font-size: 0.75rem;
+  color: var(--color-muted, var(--color-brass));
+}
+
 /* --------------------------------------------------------------------------
    Layout: hour list + hour view
    -------------------------------------------------------------------------- */