Reading map: honour reduced-motion for the orbit; give /knoebels a real nav link

Two follow-ups on yesterday's hero.

The `prefers-reduced-motion` branch only skipped the trace *animation* — the
scene kept orbiting continuously, which is precisely what a reader who asked for
reduced motion is asking not to get, on the homepage no less. The cloud now
holds still; it still renders in full.

/knoebels was reachable only from the homepage crowd strip, and that strip is
hidden whenever the park API is unreachable — so an API outage made the page
unreachable from anywhere on the site. It gets a sidebar entry, the same way
/notebooks does, since neither is a vault note that buildNavTree could carry.

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

src/layouts/Base.astro

@@ -181,6 +181,22 @@ const pageUrl = new URL(Astro.url.pathname, Astro.site);
             </div>
           )
         }
+        {/* Standalone pages — not vault notes, so buildNavTree cannot carry them.
+            /knoebels in particular is otherwise reachable only from the homepage
+            strip, which is hidden whenever the park API is unreachable. */}
+        <div class="sidebar-section">
+          <p class="sidebar-title">elsewhere</p>
+          <ul class="nav-tree">
+            <li>
+              <a
+                href="/knoebels"
+                aria-current={navPath === '/knoebels' ? 'page' : undefined}
+              >
+                Knoebels park map
+              </a>
+            </li>
+          </ul>
+        </div>
       </aside>
       {
         showToc && (

src/lib/reading-map.js

@@ -306,7 +306,10 @@ export function build(container, data) {
     const dt = Math.min((now - last) / 1000, 0.05);
     last = now;
 
-    if (!paused) world.rotation.y += ORBIT_RATE * dt;
+    // `reduced` stops the orbit outright, not just the trace draw. This sits on a public
+    // homepage, and a continuously rotating scene is exactly what a reader who asked for
+    // reduced motion is asking not to get. The cloud still renders — it just holds still.
+    if (!paused && !reduced) world.rotation.y += ORBIT_RATE * dt;
 
     elapsed += dt;
     const cycle = DRAW_SECONDS + HOLD_SECONDS;