Update reference docs: fix event names, add demos, document sx-boost target

- Remove sx:afterSettle (not dispatched), rename sx:sendError → sx:requestError
- Add sx:clientRoute event (Phase 3 client-side routing)
- Add working demos for all 10 events (afterRequest, afterSwap, requestError,
  clientRoute, sseOpen, sseMessage, sseError were missing demos)
- Update sx-boost docs: configurable target selector, client routing behavior
- Remove app-specific nav logic from orchestration.sx, use sx:clientRoute event
- Pass page content deps to sx_response for component loading after server fallback

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/static/scripts/body.js

@@ -737,6 +737,26 @@ document.body.addEventListener('click', function (e) {
 
 
 
+// ============================================================================
+// Client-side route nav selection
+//    - Updates aria-selected on sub-nav links after client-side routing
+//    - Scoped to <nav> elements (top-level section links are outside <nav>)
+// ============================================================================
+
+document.body.addEventListener('sx:clientRoute', function (e) {
+  var pathname = e.detail && e.detail.pathname;
+  if (!pathname) return;
+  // Deselect all sub-nav links (inside <nav> elements)
+  document.querySelectorAll('nav a[aria-selected]').forEach(function (a) {
+    a.setAttribute('aria-selected', 'false');
+  });
+  // Select the matching link
+  document.querySelectorAll('nav a[href="' + pathname + '"]').forEach(function (a) {
+    a.setAttribute('aria-selected', 'true');
+  });
+});
+
+
 // ============================================================================
 // Scrolling menu arrow visibility (replaces hyperscript scroll/load handlers)
 // Elements with data-scroll-arrows="arrow-class" show/hide arrows on overflow.