Make day-nav/language-toggle real links, group hours into rows

Day navigation (prev/today/next) and the language toggle were plain
buttons wired to click handlers only; switched them to real <a href>
elements (built via router's new exported urlFor) so right-click,
middle-click, and open-in-new-tab work, with a click handler that
still SPA-routes on a plain left-click and lets modified clicks fall
through to normal browser navigation.

Language selection is now reflected in the URL as a ?lang= query
param (parsed/pushed by router.ts, omitted for the default single-
English case to keep that URL clean), so a shared link preserves the
viewer's chosen language(s).

hour-list.ts now groups the 8 hours into three traditional rows
(night office, day hours, evening) instead of one flat wrapped list.

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

src/ui/styles.css

@@ -198,9 +198,16 @@ button:focus-visible {
   padding: var(--space-3) var(--space-2);
 }
 
+.hour-list-nav {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-2);
+}
+
 .hour-list {
   display: flex;
   flex-wrap: wrap;
+  gap: var(--space-2);
   list-style: none;
   margin: 0;
   padding: 0;
@@ -239,6 +246,12 @@ button:focus-visible {
   opacity: 0.85;
 }
 
+.hour-sep {
+  display: flex;
+  align-items: center;
+  color: var(--color-border);
+}
+
 .hour-status {
   font-size: 0.7rem;
   text-transform: uppercase;