fix(kami-deck): sync deck transform with host-driven .active changes

The previous fix added a local od:slide listener but the host bridge in
apps/web/src/runtime/srcdoc.ts also listens for the same message and
calls setActive() (toggles .slide.active) without driving the deck
transform. Both listeners fired, the bridge re-read the just-toggled
active class, and overshot by one — and the bridge's restoreInitialSlide
path could move .active without a message at all, leaving the deck on
the original transform.

Stop the bridge from double-handling by calling stopImmediatePropagation
in the local listener (registered first because the bridge script is
appended to </body>), and add a MutationObserver that pulls the deck
transform onto whichever slide currently carries .active so the bridge's
direct setActive calls (notably the initial-slide restore) move the deck
too.

Generated-By: looper 0.4.0 (runner=fixer, agent=claude-code)

skills/kami-deck/example.html

@@ -1051,11 +1051,19 @@ strong { font-weight: 500; }
   /* Host-driven navigation: Open Design's host bridge classifies this deck
      as class-driven (because go() toggles .slide.active) but the visible
      slide is moved by deck.style.transform, which the bridge can't drive.
-     Route od:slide messages through the local go()/jump so toolbar
-     next/prev and initialSlideIndex restore actually shift the deck. */
+     Two cooperating handlers keep the deck in sync with the host:
+       1. An od:slide message listener routes host nav through go() and
+          calls stopImmediatePropagation() so the bridge's own listener
+          (registered after this one) doesn't run a second time and
+          overshoot by re-reading the freshly-toggled .active class.
+       2. A MutationObserver on each slide watches .active and pulls the
+          deck transform onto the active index for class changes that
+          don't come through a message — chiefly the bridge's
+          restoreInitialSlide path, which calls setActive() directly. */
   addEventListener('message', function (e) {
     var data = e && e.data;
     if (!data || data.type !== 'od:slide') return;
+    if (typeof e.stopImmediatePropagation === 'function') e.stopImmediatePropagation();
     if (data.action === 'go' && typeof data.index === 'number') go(data.index);
     else if (data.action === 'next') go(idx + 1);
     else if (data.action === 'prev') go(idx - 1);
@@ -1063,6 +1071,19 @@ strong { font-weight: 500; }
     else if (data.action === 'last') go(total - 1);
   });
 
+  if (typeof MutationObserver !== 'undefined') {
+    var syncFromActiveClass = function () {
+      for (var i = 0; i < slides.length; i++) {
+        if (slides[i].classList && slides[i].classList.contains('active') && i !== idx) {
+          go(i);
+          return;
+        }
+      }
+    };
+    var mo = new MutationObserver(syncFromActiveClass);
+    slides.forEach(function (s) { mo.observe(s, { attributes: true, attributeFilter: ['class'] }); });
+  }
+
   go(0);
 })();
 </script>